Cylindrical battery cell, battery apparatus and electrical device

Abstract

Provided in the present application are a cylindrical battery cell, a battery apparatus and an electrical device. The cylindrical battery cell comprises a casing, an electrode assembly and a current collecting component. At least part of the electrode assembly and at least part of the current collecting component are arranged in the casing. The electrode assembly is a winding structure and comprises two electrode sheets having opposite polarities. At least one electrode sheet comprises an electrode sheet body and a tab arranged in the axial direction of the cylindrical battery cell. At least part of the electrode sheet body is coated with an active material layer, and at least part of the tab is not coated with the active material layer. The tab comprises a plurality of cut segments distributed in the winding direction of the electrode assembly, a cut-off groove being provided between any two adjacent cut segments in the winding direction. Each cut segment comprises a bending section, which comprises the end face of the cut segment away from the electrode sheet body, the bending section bending relative to the electrode sheet body in a direction close to the central axis of the cylindrical battery cell. The current collecting component is arranged on the side of the tab away from the electrode sheet body, at least some of the bending sections of the plurality of cut segments being welded to the current collecting component.

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 cycle performance 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 the cycle performance of the cylindrical battery cell.

[0005] In a first aspect, embodiments of this application provide a cylindrical battery cell, comprising a housing, an electrode assembly, and a current collector, wherein at least a portion of the electrode assembly and at least a portion of the current collector are disposed within the housing. The electrode assembly is a wound structure and includes two electrodes with opposite polarities. At least one electrode includes an electrode body and a tab arranged along the axial direction of the cylindrical battery cell. 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. The 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. Each segment includes a bent section, the bent section including an end face of the segment away from the electrode body, and the bent section is bent relative to the electrode body in a direction close to the central axis of the cylindrical battery cell. The current collector is disposed on the side of the tab away from the electrode body, and at least a portion of the bent sections of the plurality of segments is welded to the current collector.

[0006] In this embodiment, by providing a cut-off groove, the size of a single segment along the winding direction can be reduced, the binding force between segments can be reduced, and the bending segment can be facilitated by bending towards the central axis of the cylindrical battery cell. Since the bending segment of each segment bends towards the central axis of the cylindrical battery cell, the flatness of the surface of the tab opposite the current collector can be improved, the risk of poor soldering between the tab and the current collector can be reduced, the resistance between the current collector and the tab can be reduced, and the cycle performance of the cylindrical battery cell can be improved.

[0007] In some embodiments, each segment has a connecting end face axially facing the electrode body, the dimension of which along the winding direction is L1; in a projection plane perpendicular to the axial direction, the straight-line distance between the orthographic projections of the two ends of the connecting end face along the winding direction is L2. At least a portion of the plurality of segments satisfies: 95% ≤ L2 / L1 ≤ 99.5%.

[0008] In this embodiment, setting L2 / L1 to greater than or equal to 95% balances the curvature of the wafer and its dimensions along the winding direction, reduces redundancy during bending, improves the flatness of the surface of the tab opposite the current collector, reduces the risk of poor soldering between the tab and the current collector, reduces the resistance between the current collector and the tab, and improves the cycle performance of the cylindrical battery cell. Setting L2 / L1 to less than or equal to 99.5% allows the connection end face of the wafer to have a larger current-carrying area. When the wafer is welded to the current collector, this increases the current-carrying capacity, reduces the resistance of the cylindrical battery cell, and improves the cycle performance of the cylindrical battery cell.

[0009] In some embodiments, at least a portion of the plurality of segments satisfies: 96% ≤ L2 / L1 ≤ 99%. Embodiments of this application can further reduce the resistance of cylindrical battery cells and improve their cycle performance.

[0010] In some embodiments, the plurality of segments includes at least two first segments, wherein the first segments satisfy: 95% ≤ L2 / L1 ≤ 99.5%. The current collector is welded to the first segments. By setting at least two first segments in this application embodiment and welding the current collector to the first segments, the risk of poor soldering between the tab and the current collector can be reduced, the resistance between the current collector and the tab can be decreased, and the cycle performance of the cylindrical battery cell can be improved.

[0011] In some embodiments, the plurality of segments includes a first segment, the first segment satisfying: 95% ≤ L2 / L1 ≤ 99.5%. The ratio of the number of first segments to the total number of segments is greater than or equal to 80%. Having a larger number of first segments can improve the flatness of the surface of the tab opposite to the current collector, reduce the risk of poor soldering between the tab and the current collector, reduce the resistance between the current collector and the tab, and improve the cycle performance of the cylindrical battery cell.

[0012] In some embodiments, the electrode has a winding start end and a winding end end at its two ends along the winding direction; 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 plurality of segments includes at least one second segment, which is wound at least one turn; the segment furthest from the winding start end along the winding direction is the second segment.

[0013] The second segment can bind the first segment from the outer periphery, thereby reducing the radial deformation of the first segment under the extrusion of the current collector when welding the first segment and the current collector, improving the stability of the contact between the first segment and the current collector during the welding process, reducing the risk of poor welding, reducing the resistance between the current collector and the tab, and improving the cycle performance of the cylindrical battery cell.

[0014] In some embodiments, the multiple segments consist of multiple first segments and a second segment. This application embodiment provides only one second segment, which can reduce the wrinkled area on the surface of the tab opposite to the current collector, improve the flatness of the surface of the tab opposite to the current collector, reduce the risk of poor soldering between the tab and the current collector, reduce the resistance between the current collector and the tab, and improve the cycle performance of the cylindrical battery cell.

[0015] In some embodiments, the current collector is not welded to the second segment. The second segment is wound at least one turn, resulting in significant redundancy when bent, causing wrinkles in the bent section. By eliminating the need for welding the current collector to the second segment, the risk of incomplete soldering is reduced.

[0016] In some embodiments, each segment has a connecting end face axially facing the electrode body. Axially, the connecting end face is spaced apart from the bending segment. Embodiments of this application can increase the distance between the bending segment and the electrode body, reducing the risk of the bending segment inserting between two electrode bodies. Furthermore, spacing the connecting end face from the bending segment can reduce the force on the connecting end face during the bending process of the segment, reducing stress concentration, lowering the risk of segment tearing, and improving reliability.

[0017] In some embodiments, the electrode has a winding start end and a winding end end at its two ends along the winding direction; 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 plurality of segments includes at least one second segment, which is wound at least one turn; the segment furthest from the winding start end along the winding direction is the second segment. The second segment can bind the other segments from the outer periphery, thereby reducing the risk of the tabs bulging outwards, deforming, or tearing radially in the electrode assembly when the tabs are compressed, thus improving the reliability of the cylindrical battery cell.

[0018] In some embodiments, the number of turns of the second segment along the winding direction is less than or equal to 5. The second segment has a large redundancy when bent, and wrinkles easily appear in the bent section. This embodiment sets the number of turns of the second segment to less than or equal to 5, which can reduce the wrinkled area on the end face of the tab facing the current collector, reduce the risk of poor soldering, and reduce the resistance of the cylindrical battery cell.

[0019] In some embodiments, the orthographic projection of the current collector component does not overlap with the orthographic projection of the second segment in a projection plane perpendicular to the axial direction. By avoiding the second segment, the current collector component can reduce the impact of the wrinkled area of ​​the second segment on the current collector component, improve the stability of the direct contact between the current collector component and the bent section of the first segment, and reduce the risk of poor soldering.

[0020] 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 adjacent segments along the winding direction form a cutting groove, and the bottom surface of the cutting groove is formed on one 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.

[0021] In some embodiments, each piece has a connecting end face connected to the transition connection portion, and the dimension of the connecting end face along the winding direction is L1. The sum of the axial dimensions of the transition connection portion and the piece is L3, where 0.01 ≤ L3 / L1 ≤ 0.3. Setting L3 / L1 to be 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. In this embodiment, L3 / L1 is limited to be greater than or equal to 0.01 to reduce the difficulty of bending the piece.

[0022] In some embodiments, the axial dimension of the transition connection is L4, where 0.1mm ≤ L4 ≤ 2mm. Limiting L4 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, L4 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.

[0023] In some embodiments, at least one electrode includes a positive electrode, which comprises an electrode body, a tab, and an insulating layer. Neither the tab nor the transition connection portion of the positive electrode is coated with an active material layer, and the insulating layer is disposed at the transition connection portion. By providing an insulating layer, this embodiment reduces the risk of short circuits caused by burrs on the negative electrode contacting the transition connection portion of the positive electrode, thus improving reliability. Furthermore, by placing the insulating layer at the transition connection portion, this embodiment reduces the stress transmitted to the insulating layer during bending of the electrode, thereby reducing the risk of the insulating layer detaching.

[0024] In some embodiments, the electrode tab has multiple cutting grooves, and the cutting grooves and the segments are arranged alternately along the winding direction. By providing multiple segments and multiple cutting grooves, it is beneficial to achieve directional bending of the segments. By providing multiple cutting grooves, the binding effect between the segments can be reduced.

[0025] In some embodiments, the axial dimension of the sheet along the winding direction tends to decrease in the direction away from the electrode body. Embodiments of this application can reduce the dimension of the sheet at the bend along the winding direction, thereby reducing the redundancy of the sheet during bending, improving the flatness of the surface of the tab opposite the current collector, reducing the risk of poor soldering between the tab and the current collector, reducing the resistance between the current collector and the tab, and improving the cycle performance of the cylindrical battery cell.

[0026] In some embodiments, the size of the bent segment of the electrode assembly in the radial direction is greater than or equal to 2 mm. Embodiments of this application can increase the radial size of the bent segment and increase the number of layers of bent segments stacked in the axial direction, thereby reducing the risk of burn-through and increasing the number of bent segments welded to the current collector, increasing the current flow area, and improving the cycle performance of the cylindrical battery cell.

[0027] In some embodiments, the bent segments of multiple segments form an overlapping region. At least a portion of the overlapping region has an axial dimension greater than or equal to 100 μm, and the portion of the overlapping region with an axial dimension greater than or equal to 100 μm is welded to the current collector. Embodiments of this application can reduce the risk of electrode tabs being soldered through and improve reliability.

[0028] In some embodiments, the electrode tab includes a first electrode tab winding portion and a second electrode tab winding portion located outside the first electrode tab winding portion. A plurality of segments are formed in the second electrode tab winding portion. Axially, the segments extend beyond the first electrode tab winding portion in a direction away from the electrode body. The current collector is not welded to the first electrode tab winding portion.

[0029] In this embodiment, by providing a first tab winding portion, the distance between the wafer and the central axis can be increased, the curvature of the wafer can be reduced, the redundancy of the wafer during bending can be decreased, the flatness of the surface of the tab opposite to the current collector can be improved, the risk of poor soldering between the tab and the current collector can be reduced, the resistance between the current collector and the tab can be reduced, and the cycle performance of the cylindrical battery cell can be improved. The current collector is not welded to the first tab winding portion, which can further reduce the risk of poor soldering.

[0030] In some embodiments, the length of the second tab winding portion is greater than the length of the first tab winding portion in the winding direction. The larger length of the second tab winding portion in the winding direction facilitates an increase in the radial dimension of the second tab winding portion in the electrode assembly, which in turn facilitates an increase in the welding area between the current collector and the tab, thereby improving the current-carrying capacity of the cylindrical battery cell.

[0031] In some embodiments, at least one electrode has a winding start end and a winding end end at both ends along the winding direction of the electrode assembly, a first electrode tab winding portion has a winding start end, and a second electrode tab winding portion has a winding end end. A first notch is provided on the portion of the electrode tab near the winding start end; along the winding direction, the first notch is located on one side of the plurality of segments near the winding start end; along the direction from the electrode body to the electrode tab, the first notch is located on one side of the first electrode tab winding portion.

[0032] By incorporating the first notch, the axial dimension of the first tab winding portion can be reduced, eliminating the need for bending of the more curved portion. This improves the flatness of the surface of the tab opposite the current collector, reduces the risk of poor soldering between the tab and the current collector, decreases the resistance between the current collector and the tab, and improves the cycle performance of the cylindrical battery cell. The first notch also provides space for the sectional piece near the central axis, reducing the risk of excessively thick stacking of the sectional piece in the center of the tab.

[0033] In some embodiments, at least one electrode has a winding start end and a winding end at both ends along the winding direction, 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.

[0034] 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.

[0035] In some embodiments, the housing is provided with a pressure relief portion at at least one end along the axial direction, and 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.

[0036] When a cylindrical battery cell experiences thermal runaway due to an unexpected event such as a short circuit, the internal pressure of the casing increases. The pressure relief section opens, forming an exhaust channel, through which the high-temperature gas inside the casing is discharged. 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. During the thermal runaway process of the cylindrical battery cell, at least a portion of the electrode body corresponding to the first electrode lug winding portion can be released to the outside of the casing through the exhaust channel under the action of gas pressure, thereby rapidly relieving pressure, reducing the risk of cylindrical battery cell explosion, and improving the reliability of the cylindrical battery cell.

[0037] In some embodiments, the electrode includes a first electrode winding portion, and a first electrode tab winding portion is formed on a portion of the first electrode winding portion. On a projection plane perpendicular to the axial direction, the orthographic projection of the first electrode winding portion lies within the orthographic projection of the pressure relief portion, which is configured to at least partially open and form an exhaust passage during pressure relief, through which at least a portion of the first electrode winding portion is discharged to the outside of the housing.

[0038] In this embodiment, on the one hand, during the process of at least a portion of the first electrode winding being ejected through the exhaust channel, electrode fragments, high-temperature gases, electrolyte, and other substances can also be ejected along with the first electrode winding, thereby rapidly releasing pressure. On the other hand, since the first electrode winding is located in the middle of the electrode assembly, after at least a portion of the first electrode winding 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 gases. After at least a portion of the first electrode winding is discharged through the exhaust channel, the electrode remaining in the casing becomes more porous, facilitating the flow of gas between the electrodes. In summary, this embodiment can help increase the exhaust rate, reduce the risk of cylindrical battery cell explosion, and improve the reliability of cylindrical battery cells during thermal runaway.

[0039] 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 at intervals, and 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.

[0040] 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.

[0041] In some embodiments, the orthographic projection of the bottom surface of at least one cut-off groove lies within the orthographic projection of the pressure relief portion in a projection plane perpendicular to the axial direction. By providing the cut-off groove, the mutual binding effect between adjacent segments in the winding direction is weakened. A portion of the electrode body corresponding to the second tab winding portion (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 cut-off 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.

[0042] In some embodiments, at least a portion of the bent sections of the plurality of segments are welded to the current collector to form a first weld portion. On a projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the first weld portion have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the 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 tab winding portion and a second arc line passing through the second projection endpoint and surrounding the first tab winding portion is a 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 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. Embodiments of this application can reduce the impact of cutting off grooves on the number of layers of the bent sections stacked axially, reduce the risk of the tab being welded through, and improve welding strength.

[0043] 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 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 region between a third arc line passing through the third projection endpoint and surrounding the first tab winding portion, and a fourth arc line passing through the fourth projection endpoint and surrounding the first tab winding portion, is a second transverse region. At least some cut-off slots form a second set of cut-off slots, in which the orthographic projection of the bottom surface of all cut-off slots lies within the second transverse region. In the second set of cut-off slots, the number of turns of a single cut-off slot is ≤3; and / or, in the second set of cut-off slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

[0044] The embodiments of this application can reduce the impact of the cut-off groove on the strength of the portion of the electrode corresponding to the second transverse region, reduce the risk of collapse of the portion of the electrode corresponding to the second transverse region, thereby enabling the electrode to stably support the area of ​​the current collector that needs to be welded to the electrode terminal, reduce the risk of incomplete welding, and improve the welding strength.

[0045] 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, and the first tab and the second tab are respectively disposed at opposite ends of the electrode body along the axial direction. Along the axial direction, both ends of the electrode assembly are provided with current collectors, and the current collectors at both ends of the electrode assembly are respectively a first current collector and a second current collector; the first current collector is welded to a section of the first tab; the second current collector is welded to a section of the second tab.

[0046] In some embodiments, the housing includes a first end wall, a second end wall, and a side wall, with the first and second end walls respectively located at opposite ends of the side wall along the axial direction. The cylindrical battery cell includes an electrode terminal located on the first end wall. A first tab is electrically connected to the electrode terminal via a first current collector, and a second tab is electrically connected to the first end wall via a second current collector and the side wall. The electrode terminal and the first end wall can serve as two exposed electrodes of the cylindrical battery cell. The electrode terminal and the first end wall being located on the same side facilitates the assembly of multiple cylindrical battery cells into a group, simplifying the structure of the battery device.

[0047] In some embodiments, the second end wall is welded to the second current collector and electrically connected to the side wall. The second end wall and the second current collector are arranged axially. Welding the second end wall to the second current collector helps to increase the welding area between the second end wall and the second current collector, thereby improving the current carrying capacity of the cylindrical battery cell.

[0048] In some embodiments, the sidewall has an inwardly protruding convex portion, and the second current collector is connected to the convex portion. Connecting the second current collector to the convex portion can shorten the conductive path between the second tab and the first end wall, reduce resistance, reduce heat generation, and improve the cycle performance of the cylindrical battery cell.

[0049] 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. The second current collector is connected to the protrusion from the outside, which can reduce assembly difficulty.

[0050] Secondly, embodiments of this application provide a battery device comprising a plurality of cylindrical battery cells provided in any of the embodiments of the first aspect.

[0051] Thirdly, embodiments of this application provide an electrical device including a battery device provided in any of the embodiments of the second aspect, the battery device being used to provide electrical energy. Attached Figure Description

[0052] 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.

[0053] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0054] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application;

[0055] Figure 3 is a schematic diagram of the battery module shown in Figure 2;

[0056] Figure 4 is a schematic diagram of the structure of a cylindrical battery cell in some embodiments of this application;

[0057] Figure 5 is an exploded schematic diagram of a cylindrical battery cell in some embodiments of this application;

[0058] Figure 6 is a cross-sectional schematic diagram of a cylindrical battery cell provided in some embodiments of this application;

[0059] Figure 7 is an enlarged view of Figure 6 at box A;

[0060] Figure 8 is an enlarged view of the area in box B of Figure 6;

[0061] Figure 9 is a cross-sectional schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0062] Figure 10 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.

[0063] Figure 11 is a schematic diagram of the electrode of a cylindrical battery cell provided in some embodiments of this application in a flattened state;

[0064] Figure 12 is a cross-sectional view of the electrode shown in Figure 11 along the CC direction;

[0065] Figure 13 is a schematic diagram of the connection end face of the tab of a cylindrical battery cell provided in some embodiments of this application;

[0066] Figure 14 is an enlarged view of Figure 11 at the circular frame;

[0067] Figure 15 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;

[0068] Figure 16 is an enlarged view of Figure 15 at the boxed area;

[0069] Figure 17 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application;

[0070] Figure 18 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application;

[0071] Figure 19 is an enlarged view of Figure 18 at the boxed area;

[0072] Figure 20 is a schematic diagram of the current collector of a cylindrical battery cell provided in some embodiments of this application;

[0073] Figure 21 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application.

[0074] The reference numerals in the attached drawings are explained as follows: 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; 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; 1122. Second tab winding portion; 1123. Section; 11231. Bending section; 11232. Transition section; 1123a. Connecting end face; 1123b. First end; 1123c. Second end; 1124, Cut-off groove; 11241, Groove bottom surface; 1124a, First set of cut-off grooves; 1124b, Second set of cut-off grooves; 1125, Transition connection part; 1126, First segment; 1127, Second segment; 112a, First electrode tab; 112b, Second electrode tab; 113, Insulating layer; 11a, Positive electrode; 11b, Negative electrode; 12, Isolator; 13, First electrode winding part; 14, Second electrode winding part; 15, Center hole; 20. Outer shell; 20a. Second end wall; 21. Shell; 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; E1. Winding start end; E2. Winding end; E3. First projection end point; E4. Second projection end point; E5. Third projection endpoint; E6, fourth projection endpoint; G1, first notch; G2, second notch; 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

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] In this application, "multiple" means two or more (including two).

[0082] 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.

[0083] A battery device can refer to a single physical module comprising one or more cylindrical battery cells to provide higher voltage and capacity.

[0084] 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.

[0085] 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.

[0086] Electrode assemblies typically include tabs that allow current to be drawn from the electrode assembly. Cylindrical cell units usually have current collectors that guide the current from the tabs to the electrode lead-out structures of the cylindrical cell.

[0087] In related technologies, the end of the tab is bent to form a dense end face by flattening, and the current collector is welded to the end face of the tab. However, the tab is usually a continuous structure extending along the winding direction, and its bending direction during the flattening process is irregular, resulting in uneven end face wrinkles. This affects the reliability of the welding between the tab and the current collector, increases the resistance between the current collector and the tab, and affects the cycle performance of the cylindrical battery cell.

[0088] In view of this, the present application provides a technical solution that forms multiple independently bendable segments by opening cutting grooves on the tab, thereby helping to achieve directional bending of the tab, reducing wrinkles on the end face of the tab, improving the reliability of welding between the tab and the current collector, reducing the resistance between the current collector and the tab, and improving the cycle performance of the cylindrical battery cell.

[0089] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0090] Figure 1 is a schematic diagram of the structure of a vehicle provided in some embodiments of this application.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] Figure 2 is a schematic diagram of a battery device provided in some embodiments of this application.

[0095] In some embodiments, the battery device 2 may include one or more battery cell assemblies for providing voltage and capacity.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] In some embodiments, the housing 5 is used to house cylindrical battery cells, and the housing 5 can have various structures.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] In some embodiments, the battery device 2 may be an energy storage device.

[0106] 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.

[0107] In some embodiments, the energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0108] Figure 3 is a schematic diagram of the battery module shown in Figure 2.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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).

[0115] 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;

[0116] 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.

[0117] 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.

[0118] The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0119] 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.

[0120] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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 112, a portion of which can extend outside housing 20.

[0128] Optionally, the electrode assembly 10 is entirely housed within the housing 20.

[0129] 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.

[0130] In some embodiments, along the axial direction Z of the cylindrical battery cell 7, 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.

[0131] 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.

[0132] The first electrode lead-out portion 7a and the second electrode lead-out portion 7b are insulated from each other.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] In some embodiments, the second electrode lead-out portion 7b may be the first end wall 211.

[0140] 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.

[0141] In some embodiments, the electrode terminal 30 is riveted to the first end wall 211.

[0142] 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.

[0143] 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.

[0144] In some embodiments, the cylindrical battery cell 7 includes a current collector 40, which is electrically connected to the tab 112.

[0145] 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.

[0146] In some embodiments, the current collector 40 is welded to the tab 112.

[0147] 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.

[0148] 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.

[0149] In some embodiments, electrode terminals 30 are welded to the first current collector 40a.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] In some embodiments, the electrode terminal 30 has a terminal recess 31 on the side opposite to the first current collector 40a.

[0154] 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.

[0155] In some embodiments, the bottom wall of the terminal recess 31 is provided with a through hole, which can be used to inject electrolyte.

[0156] 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.

[0157] In some embodiments, at least a portion of the cover plate 50 is received in the terminal recess 31.

[0158] In some embodiments, the first electrode lead-out portion 7a includes an electrode terminal 30 and a cover plate 50.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] In some embodiments, the housing 20 is provided with a pressure relief portion 61 at at least one end along the axial direction Z.

[0166] 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.

[0167] 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.

[0168] In some embodiments, a pressure relief portion 61 is disposed on the second end wall 20a.

[0169] 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.

[0170] 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 of a cylindrical battery cell provided in some embodiments of this application before the tab is bent; Figure 11 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 12 is a cross-sectional schematic diagram of the electrode sheet shown in Figure 11 along the CC direction; Figure 13 is a schematic diagram of the connecting end face of the tab of a cylindrical battery cell provided in some embodiments of this application; Figure 14 is an enlarged schematic diagram of Figure 11 at the circular frame; Figure 15 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 16 is an enlarged schematic diagram of Figure 15 at the box; Figure 17 is a schematic diagram of the electrode assembly of a cylindrical battery cell provided in some embodiments of this application.

[0171] Referring to Figures 5 to 17, this application embodiment provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, and a current collector 40. At least a portion of the electrode assembly 10 and at least a portion of the current collector 40 are 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 of the cylindrical battery cell 7. 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.

[0172] The tab 112 includes a plurality of segments 1123 distributed along the winding direction V of the electrode assembly 10. A cut-off groove 1124 is provided between any two adjacent segments 1123 along the winding direction V. Each segment 1123 includes a bent section 11231, which includes the end face of the segment 1123 away from the electrode body 111. The bent section 11231 is bent relative to the electrode body 111 towards the central axis P5 of the cylindrical battery cell 7. A current collector 40 is disposed on the side of the tab 112 away from the electrode body 111, and at least a portion of the bent sections 11231 of the plurality of segments 1123 are welded to the current collector 40.

[0173] As an example, two pole pieces 11 with opposite polarities can be wound along the winding direction V.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.).

[0179] In some examples, the positive electrode 11a includes an electrode body 111 and a tab 112.

[0180] 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 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 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.

[0181] 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.

[0182] In other examples, the negative electrode 11b includes an electrode body 111 and an electrode tab 112.

[0183] 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 7. 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 7 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] The dimensions of the multiple segments 1123 in the winding direction V can be the same or different. There can be multiple cutting grooves 1124, and the dimensions of the multiple cutting grooves 1124 in the winding direction V can be the same or different.

[0188] The cut-off piece 1123 can be bent entirely relative to the electrode body 111, that is, the cut-off piece 1123 only includes the bending section 11231; alternatively, a portion of the cut-off piece 1123 is bent relative to the electrode body 111. For example, the cut-off piece 1123 also includes a transition section 11232, which connects the electrode body 111 and the bending section 11231. The bending section 11231 is bent relative to the transition section 11232 in a direction close to the central axis P5 of the cylindrical battery cell 7.

[0189] The cut-off piece 1123 can be directly connected to the electrode body 111, or it can be connected to the electrode body 111 through other parts of the electrode tab 112.

[0190] The current collector 40 can be welded to a portion of the bends 11231 of the multiple segments 1123, or it can be welded to the bends 11231 of each segment 1123.

[0191] In this embodiment, by providing the cut-off groove 1124, the size of a single piece 1123 along the winding direction V can be reduced, the binding force between the pieces 1123 can be reduced, and the bending segment 11231 can be bent towards the central axis P5 of the cylindrical battery cell 7. The bending segment 11231 of each piece 1123 is bent towards the central axis P5 of the cylindrical battery cell 7, which can improve the flatness of the surface of the tab 112 opposite to the current collector 40, reduce the risk of poor soldering between the tab 112 and the current collector 40, reduce the resistance between the current collector 40 and the tab 112, and improve the cycle performance of the cylindrical battery cell 7.

[0192] By setting the bending direction of the cut-off groove 1124 and the cut piece 1123, the risk of the cut piece 1123 being inserted upside down between the electrode bodies 111 of the two electrode pieces 11 due to irregular bending can be reduced, thereby reducing the risk of short circuit and improving the reliability of the battery cell.

[0193] In some embodiments, the bent segment 11231 is bent inward along the radial direction R of the electrode assembly 10.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] In some embodiments, the liquid electrolyte includes an electrolyte salt and a solvent.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0205] 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.

[0206] 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.

[0207] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0208] In some embodiments, the tab 112 may be cylindrical.

[0209] In some embodiments, the cut-off piece 1123 is bent by a process or a smoothing process.

[0210] In some embodiments, at least a portion of the bent segments 11231 of the plurality of segments 1123 are welded to the current collector 40 to form a first welded portion W1.

[0211] There may be one or more first welded portions W1. Optionally, multiple first welded portions W1 are arranged at circumferential intervals along the cylindrical battery cell 7.

[0212] In some embodiments, a plurality of first welded portions W1 are arranged radially.

[0213] In one embodiment, the first weld portion W1 extends radially R along the electrode assembly 10.

[0214] In some embodiments, each segment 1123 has a connecting end face 1123a oriented along the axial direction Z toward the electrode body 111, the dimension of the connecting end face 1123a along the winding direction V being L1; in a projection plane perpendicular to the axial direction Z, the straight-line distance between the orthographic projections of the two ends of the connecting end face 1123a along the winding direction V is L2. At least a portion of the plurality of segments 1123 satisfies: 95% ≤ L2 / L1 ≤ 99.5%.

[0215] The connecting end face 1123a can be directly connected to the electrode body 111; alternatively, other structures may be provided between the connecting end face 1123a and the electrode body 111.

[0216] As an example, after the electrode 11 is flattened, the dimension of the connecting end face 1123a along the length direction X of the electrode 11 can be equal to L1.

[0217] The connecting end face 1123a has a first end 1123b and a second end 1123c that are arranged opposite to each other along the winding direction V; in the projection plane perpendicular to the axis Z, the minimum straight-line distance between the orthographic projection of the first end 1123b and the orthographic projection of the second end 1123c can be L2.

[0218] In the embodiments of this application, each slice 1123 may satisfy 95% ≤ L2 / L1 ≤ 99.5%, or a portion of the slices 1123 may satisfy 95% ≤ L2 / L1 ≤ 99.5%.

[0219] As an example, L2 / L1 ratios are 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, or 99.5%.

[0220] In this embodiment, setting L2 / L1 to greater than or equal to 95% balances the curvature of the segment 1123 and its dimensions along the winding direction V, reducing redundancy during bending, improving the flatness of the surface of the tab 112 opposite to the current collector 40, reducing the risk of poor soldering between the tab 112 and the current collector 40, reducing the resistance between the current collector 40 and the tab 112, and improving the cycle performance of the cylindrical battery cell 7. Setting L2 / L1 to less than or equal to 99.5% allows the connection end face 1123a of the segment 1123 to have a larger current-carrying area. When the segment 1123 is soldered to the current collector 40, this increases the current-carrying capacity, reduces the resistance of the cylindrical battery cell, and improves the cycle performance of the cylindrical battery cell 7.

[0221] For example, the current collector 40 is welded to a portion of the segment 1123. Setting L2 / L1 to less than or equal to 99.5% can make the segment welded to the current collector 40 have a larger current flow area, which is beneficial to increase the current flow capacity, reduce the resistance of the cylindrical battery cell, and improve the cycle performance of the cylindrical battery cell 7.

[0222] For example, L2 / L1 is related to both the curvature of the connecting end face 1123a and the dimension of the connecting end face 1123a along the winding direction V. The curvature of the connecting end face 1123a is determined based on its distance from the central axis P5. When the curvature of the connecting end face 1123a is constant, the smaller the dimension of the connecting end face 1123a along the winding direction V, the larger L2 / L1, the smaller the redundancy of the segment 1123 during bending, and the smaller the flow area of ​​the connecting end face 1123a; when the curvature of the connecting end face 1123a is constant, the larger the dimension of the connecting end face 1123a along the winding direction V, the smaller L2 / L1, the larger the redundancy of the segment 1123 during bending, and the larger the flow area of ​​the connecting end face 1123a. In this embodiment, setting L2 / L1 to 95%-99.5% can improve the flatness of the surface of the tab 112 opposite to the current collector 40, reduce the risk of poor soldering between the tab 112 and the current collector 40, reduce the resistance of the cylindrical battery cell, and improve the cycle performance of the cylindrical battery cell 7.

[0223] In this embodiment of the application, setting L2 / L1 to less than or equal to 99.5% can also prevent the size of the cut piece 1123 in the winding direction V from being too small, thereby reducing the risk that the cut piece 1123 will be inserted between the two electrode bodies 111 during the bending process.

[0224] In some embodiments, at least a portion of the plurality of segments 1123 satisfies: 96% ≤ L2 / L1 ≤ 99%. Embodiments of this application can further reduce the resistance of the cylindrical battery cell and improve the cycle performance of the cylindrical battery cell 7.

[0225] In some embodiments, the plurality of segments 1123 includes at least two first segments 1126, the first segments 1126 satisfying: 95% ≤ L2 / L1 ≤ 99.5%. The current collector 40 is welded to the first segments 1126.

[0226] Multiple slices 1123 can all be the first slice 1126, or a portion of them can be the first slice 1126.

[0227] In this embodiment, at least two first segments 1126 are provided, and the current collector 40 is welded to the first segments 1126. This can reduce the risk of poor soldering between the tab 112 and the current collector 40, reduce the resistance between the current collector 40 and the tab 112, and improve the cycle performance of the cylindrical battery cell 7.

[0228] In some embodiments, the first slice 1126 satisfies: 96% ≤ L2 / L1 ≤ 99%.

[0229] In some embodiments, the plurality of slices 1123 includes a first slice 1126, the first slice 1126 satisfying: 95% ≤ L2 / L1 ≤ 99.5%. The ratio of the number of first slices 1126 to the total number of slices 1123 is greater than or equal to 80%.

[0230] Optionally, the ratio of the number of first slices 1126 to the total number of slices 1123 is 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, or 100%.

[0231] In this embodiment, the first segment 1126 has a large number, which can improve the flatness of the surface of the tab 112 opposite to the current collector 40, reduce the risk of poor soldering between the tab 112 and the current collector 40, reduce the resistance between the current collector 40 and the tab 112, and improve the cycle performance of the cylindrical battery cell 7.

[0232] In some embodiments, the 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.

[0233] In the radial direction R of the electrode assembly 10, the winding end E2 is located outside the winding start end E1. 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.

[0234] In some embodiments, the plurality of segments 1123 include at least one second segment 1127, which is wound at least one turn. Along the winding direction V, the segment 1123 farthest from the winding start end E1 is the second segment 1127.

[0235] The second segment 1127 can be one or multiple.

[0236] The second segment 1127 can bind the other segments 1123 from the outer periphery, thereby reducing the risk of the tab 112 bulging outward, deforming, or tearing 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.

[0237] For example, the second segment 1127 can bind the first segment 1126 from the outer periphery, thereby reducing the radial deformation of the first segment 1126 under the compression of the current collector 40 when welding the first segment 1126 and the current collector 40, improving the stability of the contact between the first segment 1126 and the current collector 40 during the welding process, reducing the risk of poor welding, reducing the resistance between the current collector 40 and the tab 112, and improving the cycle performance of the cylindrical battery cell 7.

[0238] In some embodiments, the second segment 1127 is wound with less than or equal to 5 turns along the winding direction V.

[0239] Optionally, the number of turns of the second section 1127 is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5.

[0240] The second section 1127 has a large redundancy when bent, and the bent section 11231 of the second section 1127 is prone to wrinkles. In this embodiment, the number of turns of the second section 1127 is set to be less than or equal to 5, which can reduce the wrinkled area on the end face of the tab 112 facing the current collector 40, reduce the risk of poor soldering, and reduce the resistance of the cylindrical battery cell 7.

[0241] In some embodiments, the orthographic projection of the current collector 40 and the orthographic projection of the second segment 1127 do not overlap in the projection plane perpendicular to the Z-axis.

[0242] The current collector 40 is positioned to avoid the second section 1127, which can reduce the impact of the wrinkled area of ​​the second section 1127 on the current collector 40, improve the stability of the direct contact between the current collector 40 and the bent section 11231 of the first section 1126, and reduce the risk of poor soldering.

[0243] In some embodiments, the current collector 40 is not welded to the second segment 1127.

[0244] The second segment 1127 is wound at least one turn, resulting in significant redundancy when bent, causing wrinkles in the bent section 11231. The current collector 40 does not need to be welded to the second segment 1127, reducing the risk of incomplete welding.

[0245] In some embodiments, the plurality of segments 1123 are composed of a plurality of first segments 1126 and a second segment 1127. This embodiment of the application provides only one second segment 1127, which can reduce the wrinkled area on the surface of the tab 112 opposite to the current collector 40, improve the flatness of the surface of the tab 112 opposite to the current collector 40, reduce the risk of poor soldering between the tab 112 and the current collector 40, reduce the resistance between the current collector 40 and the tab 112, and improve the cycle performance of the cylindrical battery cell 7.

[0246] In some embodiments, each segment 1123 has a connecting end face 1123a oriented along the Z-axis toward the electrode body 111. Along the Z-axis, the connecting end face 1123a is spaced apart from the bent segment 11231.

[0247] For example, the cut-off piece 1123 also includes a transition segment 11232, which includes a connecting end face 1123a.

[0248] The embodiments of this application can increase the distance between the bending segment 11231 and the electrode body 111, reducing the risk of the bending segment 11231 being inserted between the two electrode bodies 111. In addition, by spacing the connecting end face 1123a from the bending segment 11231, the force on the connecting end face 1123a during the bending process of the cut piece 1123 can be reduced, stress concentration can be reduced, the risk of tearing of the cut piece 1123 can be reduced, and reliability can be improved.

[0249] 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.

[0250] 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.

[0251] For example, the transition connection portion 1125 extends continuously along the winding direction V.

[0252] 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.

[0253] 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.

[0254] Along the Z-axis, the segment 1123 is located entirely outside the spacer 12.

[0255] 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.

[0256] 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.

[0257] In some embodiments, each segment 1123 has a connecting end face 1123a connected to the transition connecting portion 1125, and the dimension of the connecting end face 1123a along the winding direction V is L1. The sum of the dimensions of the transition connecting portion 1125 and the segment 1123 in the axial direction Z is L3, and 0.01≤L3 / L1≤0.3.

[0258] 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 L3.

[0259] As an example, L3 / 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.

[0260] In this embodiment, setting L3 / L1 to less than or equal to 0.3 can, to a certain extent, balance the space occupied by the tab 112 in the axial Z direction and the current carrying capacity of the tab 112. In this embodiment, L3 / L1 is limited to greater than or equal to 0.01 to reduce the bending difficulty of the cut-out piece 1123.

[0261] In some embodiments, the dimension of the transition connection portion 1125 in the axial Z direction is L4, where 0.1mm≤L4≤2mm.

[0262] As an example, L4 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.

[0263] In this embodiment, L4 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, L4 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.

[0264] In some embodiments, at least one electrode 11 includes a positive electrode 11a, the positive electrode 11a includes an electrode body 111, a tab 112 and an insulating layer 113, the tab 112 and the transition connection portion 1125 of the positive electrode 11a are not coated with an active material layer 1111, and the insulating layer 113 is disposed on the transition connection portion 1125.

[0265] 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.

[0266] By providing an insulating layer 113, this embodiment of the application reduces the risk of short circuits caused by contact between burrs on the negative electrode 11b and the transition connection portion 1125 of the positive electrode 11a, thereby improving reliability. Furthermore, by placing the insulating layer 113 at the transition connection portion 1125, this embodiment reduces the stress transmitted to the insulating layer 113 during the bending process of the cut piece 1123, thus lowering the risk of the insulating layer 113 detaching.

[0267] In some embodiments, in the axial direction Z, the segment 1123 of the positive electrode 11a is spaced apart from the insulating layer 113.

[0268] In some embodiments, the thickness of the insulating layer 113 is less than the thickness of the active material layer 1111.

[0269] 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.

[0270] After the electrode 11 is flattened, the length of the insulating layer 113 is equal to the length of the active material layer 1111.

[0271] In some embodiments, in the radial direction R of the electrode assembly 10, the insulating layer 113 separates the transition connection portion 1125 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, so as to reduce the risk of short circuit.

[0272] 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.

[0273] 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.

[0274] When thermal runaway occurs in the cylindrical battery cell 7, at least some of the multiple segments 1123 can be separated 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, 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.

[0275] In some embodiments, in the axial direction Z, the size of the slit 1123 along the winding direction V tends to decrease in the direction away from the electrode body 111.

[0276] 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.

[0277] The embodiments of this application can reduce the size of the bending point of the segment 1123 along the winding direction V, thereby reducing the redundancy of the segment 1123 during bending, improving the flatness of the surface of the tab 112 opposite to the current collector 40, reducing the risk of poor soldering between the tab 112 and the current collector 40, reducing the resistance between the current collector 40 and the tab 112, and improving the cycle performance of the cylindrical battery cell 7.

[0278] In some embodiments, the size of the bent segment 11231 of the cut 1123 in the radial direction R of the electrode assembly 10 is greater than or equal to 2 mm.

[0279] As an example, the dimensions of the bent segment 11231 of the cut 1123 in the radial direction R of the electrode assembly 10 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0280] The embodiments of this application can increase the size of the bending segment 11231 in the radial direction R and increase the number of layers of the bending segment 11231 stacked in the axial direction Z, thereby reducing the risk of weld burn-through and increasing the number of bending segments 11231 welded to the current collector 40, increasing the current flow area and improving the cycle performance of the cylindrical battery cell 7.

[0281] In some embodiments, the size of the bent segment 11231 of the cut 1123 in the radial direction R of the electrode assembly 10 is less than or equal to 10 mm.

[0282] The embodiments of this application can limit the maximum number of layers of the bent segments 11231 stacked in the Z-axis direction, thereby saving the space occupied by the tabs 112 in the Z-axis direction and improving the energy density.

[0283] In some embodiments, the bent segments 11231 of the plurality of segments 1123 form an overlapping region Q. At least a portion of the overlapping region Q has a dimension T in the axial direction Z greater than or equal to 100 μm, and the portion of the overlapping region Q with a dimension T greater than or equal to 100 μm in the axial direction Z is welded to the current collector 40.

[0284] The embodiments of this application can reduce the risk of the tab 112 being soldered through and improve reliability.

[0285] In some embodiments, the overlapping region Q has a size of less than or equal to 1000 μm in the axial direction Z, thereby saving the space occupied by the tab 112 in the axial direction Z and improving the energy density.

[0286] In some embodiments, in the overlapping region Q, the number of layers of the bent segment 11231 stacked along the axial direction Z is greater than or equal to 2. The overlapping region Q includes a first region in which the number of layers of the bent segment 11231 stacked along the axial direction Z is greater than or equal to 5, and the first region is welded to the current collector 40.

[0287] In some embodiments, 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. A plurality of segments 1123 are formed in the second electrode tab winding portion 1122. In the axial direction Z, the segments 1123 extend beyond the first electrode tab winding portion 1121 in a direction away from the electrode body 111. The current collector 40 is not welded to the first electrode tab winding portion 1121.

[0288] 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.

[0289] 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.

[0290] In this embodiment, by providing the first tab winding portion 1121, the distance between the segment 1123 and the central axis P5 can be increased, the curvature of the segment 1123 can be reduced, the redundancy of the segment 1123 during bending can be decreased, the flatness of the surface of the tab 112 opposite to the current collector 40 can be improved, the risk of poor soldering between the tab 112 and the current collector 40 can be reduced, the resistance between the current collector 40 and the tab 112 can be reduced, and the cycle performance of the cylindrical battery cell 7 can be improved. The current collector 40 is not welded to the first tab winding portion 1121, which can reduce the risk of poor soldering.

[0291] In some embodiments, the first electrode ear winding portion 1121 is wound to form a circular structure, and the diameter of the first electrode ear winding portion 1121 is 4mm-16mm.

[0292] In this embodiment, the diameter of the first electrode winding portion 1121 is set to be greater than or equal to 4 mm, which can provide sufficient space for the cut piece 1123, reduce the risk of the cut piece 1123 being over-stacked on the upper side of the first electrode winding portion 1121, and improve the flatness of the surface of the electrode 112 facing the current collector 40.

[0293] In this embodiment, the diameter of the first electrode winding portion 1121 is set to be less than or equal to 16 mm, which can reduce the impact of setting the first electrode winding portion 1121 on the current carrying capacity.

[0294] In some embodiments, the tab 112 includes a transition connection portion 1125. A portion of the transition connection portion 1125 is formed in the first tab winding portion 1121, and a portion of the transition connection portion 1125 is formed in the second tab winding portion 1122.

[0295] 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.

[0296] 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.

[0297] 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 welding area between the current collector 40 and the tab 112, thereby improving the current carrying capacity of the cylindrical battery cell 7.

[0298] 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, a first electrode tab winding portion 1121 has a winding start end E1, and a second electrode tab winding portion 1122 has a winding end end E2. The portion of the electrode tab 112 near the winding start end E1 has a first notch G1; along the winding direction V, the first notch G1 is located on one side of the plurality of segments 1123 near the winding start end E1; along the direction from the electrode body 111 to the electrode tab 112, the first notch G1 is located on one side of the first electrode tab winding portion 1121.

[0299] As an example, after the electrode 11 is flattened, the first notch G1 can be rectangular, triangular, trapezoidal or other shapes.

[0300] In this embodiment, by providing the first notch G1, the dimension of the first tab winding portion 1121 along the axial direction Z can be reduced, so that the first tab winding portion 1121 with a large curvature does not need to be bent, thereby improving the flatness of the surface of the tab 112 opposite to the current collector 40, reducing the risk of poor soldering between the tab 112 and the current collector 40, reducing the resistance between the current collector 40 and the tab 112, and improving the cycle performance of the cylindrical battery cell 7. The first notch G1 can also provide space for the segment 1123 near the central axis P5, reducing the risk of the segment 1123 being stacked too thickly in the middle of the tab 112.

[0301] 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.

[0302] In some embodiments, in the positive electrode 11a, in the axial direction Z, a first notch G1 is provided on the side of the insulating layer 113 opposite to the electrode body 111.

[0303] 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.

[0304] In some embodiments, at least one electrode 11 has a winding start end E1 and a winding end E2 at both ends along the winding direction V. A first electrode tab winding portion 1121 has a winding start end E1, and a second electrode tab winding portion 1122 has a winding end E2. 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. The portion of the second electrode tab winding portion 1122 near the winding end E2 has 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 electrode tab 112 away from the electrode body 111 along the axial direction Z.

[0305] As an example, after the electrode 11 is flattened, the second notch G2 can be rectangular, triangular, trapezoidal or other shapes.

[0306] As an example, the second notch G2 is provided on the side of the second segment 1127 near the winding end E2 along the winding direction V. The second notch G2 penetrates the end face of the second segment 1127 away from the electrode body 111 along the axial direction Z.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] 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.

[0311] 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.

[0312] 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.

[0313] 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.

[0314] 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 7 relative to the second notch G2.

[0315] 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.

[0316] 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.

[0317] In some embodiments, the housing 20 is provided with a pressure relief portion 61 at at least one end along the axial direction Z, and the orthographic projection of the first pole lug winding portion 1121 is located within the orthographic projection of the pressure relief portion 61 on a projection plane perpendicular to the axial direction Z.

[0318] 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, through which the high-temperature gas inside the casing 20 is discharged. The current collector 40 is not welded to the first electrode lug winding section 1121, thereby reducing the binding effect of the current collector 40 on the first electrode lug winding section 1121. During the thermal runaway process of the cylindrical battery cell 7, at least a portion of the electrode body 111 corresponding to the first electrode lug winding section 1121 can be released to the outside of the casing 20 through the exhaust channel under the action of air pressure, thereby rapidly depressurizing, reducing the risk of the cylindrical battery cell 7 exploding, and improving the reliability of the cylindrical battery cell 7.

[0319] In some embodiments, the electrode 11 includes a first electrode winding portion 13, and a first electrode tab winding portion 1121 is formed on a portion 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 lies within the orthographic projection of the pressure relief portion 61, which is configured to at least partially open and form an exhaust channel during pressure relief, through which at least a portion of the first electrode winding portion 13 is discharged to the outside of the housing 20.

[0320] 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. The second electrode body winding portion 14 includes the second electrode body winding portion 1114 and the second electrode ear winding portion 1122.

[0321] 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.

[0322] 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.

[0323] On the one 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 releasing 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 will be formed in the middle of the electrode assembly 10, which is conducive to 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 outer casing 20 will become 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 during thermal runaway of the cylindrical battery.

[0324] 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.

[0325] In some embodiments, the winding start end E1 is formed in the first electrode winding portion 13.

[0326] 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.

[0327] 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 X are flush with the two ends of the first electrode body winding portion 1113 along the length direction X.

[0328] 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.

[0329] 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.

[0330] In some embodiments, the winding end E2 is located at the second electrode winding portion 14.

[0331] 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.

[0332] 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 X are flush with the two ends of the second electrode body winding portion 1114 along the length direction X.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] In some embodiments, the tab 112 is provided with a first notch G1. By providing the first notch G1, the mutual binding effect between the first tab winding portion 1121 and the second tab winding portion 1122 can be weakened. In the event of thermal runaway of the cylindrical battery cell 7, at least a portion of the first electrode winding portion 13 can be easily discharged through the exhaust channel under the action of air 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.

[0337] 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.

[0338] 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.

[0339] 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.

[0340] 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.

[0341] 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.

[0342] 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.

[0343] 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°.

[0344] As an example, after the weak part 62 is disconnected, the pressure relief part 61 separates from the outer casing 20, thereby forming an exhaust channel.

[0345] 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.

[0346] 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.

[0347] 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.

[0348] 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.

[0349] 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.

[0350] 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.

[0351] The tab 112 can be electrically connected to the electrode terminal 30 through the current collector 40.

[0352] 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.

[0353] 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.

[0354] 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.

[0355] In some embodiments, the electrode assembly 10 is provided with a central hole 15, which extends along the axial direction Z;

[0356] 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.

[0357] 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.

[0358] In some embodiments, the central axis P5 of the cylindrical battery cell 7 passes through the central hole 15.

[0359] In some embodiments, the first electrode loop winding portion 1121 is arranged at intervals 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 in the orthographic projection of the pressure relief portion 61.

[0360] For example, the first electrode winding portion 13 is disposed around the outer periphery of the central hole 15.

[0361] 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.

[0362] 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%].

[0363] 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%.

[0364] 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.

[0365] In some embodiments, by providing the cut-off groove 1124, the obstruction of the 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 interior of the electrode assembly 10.

[0366] 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.

[0367] In this embodiment of the application, in the Z-axis direction, 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.

[0368] 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.

[0369] 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.

[0370] 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.

[0371] In some embodiments, in a projection plane perpendicular to the axial direction Z, the orthographic projection of the bottom surface 11241 of at least one cut-off groove 1124 is located within the orthographic projection of the pressure relief portion 61.

[0372] By providing the cut-off groove 1124, the mutual binding effect between adjacent segments 1123 in the winding direction V is weakened. A portion of the electrode body 111 corresponding to the second electrode lug 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 cut-off 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.

[0373] 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.

[0374] In some embodiments, at least a portion of the bent segments 11231 of the plurality of segments 1123 are welded to the current collector 40 to form a first welded portion W1. On a projection plane perpendicular to the axial direction Z, the two ends of the orthographic projection of the first welded portion W1 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 7 than the second projection endpoint E4. The area between the first arc line P1, which passes through the first projection endpoint E3 and surrounds the first electrode loop portion 1121, and the second arc line P2, which passes through the second projection endpoint E4 and surrounds the first electrode loop portion 1121, is a first transverse region Q1. At least a portion of the cut-off grooves 1124 form a first set of cut-off grooves 1124a. In the first set of cut-off grooves 1124a, the orthographic projection of the groove bottom surface 11241 of all cut-off grooves 1124 is located within the first transverse region Q1.

[0375] In some examples, the first set of cutoff slots 1124a may include all of the cutoff slots 1124. In other examples, it may include only a portion of the cutoff slots 1124.

[0376] 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 tab 112 are shown in cross-section.

[0377] 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 first welding portion W1, and the second projection endpoint E4 is the point farthest from the center of the electrode assembly 10 in the orthographic projection of the first welding portion W1. 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.

[0378] For example, there may be one or more first weld portions W1. For instance, if there are multiple first weld portions W1, 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 first weld portions W1.

[0379] 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.

[0380] On a projection plane perpendicular to the Z-axis, the orthographic projection of the first welded part W1 may have one or more first projection endpoints E3. For example, the orthographic projection of the first welded part W1 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.

[0381] On a projection plane perpendicular to the Z-axis, the orthographic projection of the first welded part W1 may have one or more second projection endpoints E4. For example, the orthographic projection of the first welded part W1 may have multiple second projection endpoints E4, and the multiple second projection endpoints E4 are equidistant from the center of the electrode assembly 10, with the second arc P2 passing through the multiple second projection endpoints E4.

[0382] For example, the first transverse region Q1 is annular. The first arc P1 and the second arc P2 are concentrically arranged. For example, the center of the first arc P1, the center of the second arc P2, and the center of the electrode assembly 10 are concentrically arranged.

[0383] In some examples, on a projection plane perpendicular to the axis Z, the first arc P1 surrounds the orthographic projection of the first pole lug winding portion 1121.

[0384] 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.

[0385] The portion of the tab 112 corresponding to the first transverse region Q1 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 first set of cut-off grooves 1124a is set to be less than or equal to 3. This can reduce the impact of opening the cut-off groove 1124 on the number of layers of the bent section 11231 stacked in the axial Z direction, reduce the risk of the tab 112 being welded through, and improve the welding strength.

[0386] 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.

[0387] The embodiments of this application can reduce the impact of opening the cut-off groove 1124 on the number of layers of the bent section 11231 stacked in the axial Z direction, reduce the risk of the tab 112 being welded through, and improve the welding strength.

[0388] 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. 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.

[0389] 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 two ends of the orthographic projection of the second welded portion W2 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 7 than the fourth projection endpoint E6. The area between the third arc line P3, which passes through the third projection endpoint E5 and surrounds the first electrode loop portion 1121, and the fourth arc line P4, which passes through the fourth projection endpoint E6 and surrounds the first electrode loop portion 1121, is the second transverse region Q2. At least a portion 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.

[0390] The second set of cut-off slots 1124b may include all cut-off slots 1124 or only a portion of the cut-off slots 1124.

[0391] 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 second welding part W2, and the fourth projection endpoint E6 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 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.

[0392] For example, there may be one or more second weld portions W2. For instance, if there are multiple second weld portions W2, 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 second weld portions W2.

[0393] 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.

[0394] On a projection plane perpendicular to the Z-axis, the orthographic projection of the second weld portion W2 may have one or more third projection endpoints E5. For example, the orthographic projection of the second weld portion W2 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, with the third arc P3 passing through the multiple third projection endpoints E5.

[0395] On a projection plane perpendicular to the Z-axis, the orthographic projection of the second weld portion W2 may have one or more fourth projection endpoints E6. For example, the orthographic projection of the second weld portion W2 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.

[0396] For example, the second transverse region Q2 is annular. The third arc P3 and the fourth arc P4 are concentrically arranged.

[0397] 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.

[0398] When welding the electrode terminal 30 and the current collector 40, the portion of the tab 112 corresponding to the second transverse region Q2 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 second set of cut-off grooves 1124b is set to be less than or equal to 3. This reduces the impact of the cut-off groove 1124 on the strength of the portion of the tab 112 corresponding to the second transverse region Q2, lowers the risk of collapse of this portion, 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, reducing the risk of incomplete welds and improving weld strength.

[0399] As an example, in the second set of cut-off slots 1124b, 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.

[0400] 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.

[0401] 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. This embodiment can reduce the impact of the cut-off grooves 1124 on the strength of the portion of the tab 112 corresponding to the second transverse region Q2, reducing the risk of collapse of the portion of the tab 112 corresponding to the second transverse region Q2. 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.

[0402] 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, 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.

[0403] 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 body 111 along the axial direction Z.

[0404] 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 a first current collector 40a and a second current collector 40b, respectively; the first current collector 40a is welded to the segment 1123 of the first tab 112a; the second current collector 40b is welded to the segment 1123 of the second tab 112b.

[0405] The first current collector 40a and the second current collector 40b may have the same or different shapes.

[0406] 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.

[0407] In some embodiments, the first current collector 40a is annular.

[0408] In some embodiments, the second current collector 40b is annular.

[0409] In some embodiments, both the first tab 112a and the second tab 112b include a first tab winding portion 1121 and a second tab winding portion 1122. The first current collector 40a is welded to the section 1123 of the second tab winding portion 1122 of the first tab 112a, but not to the first tab winding portion 1121 of the first tab 112a; the second current collector 40b is welded to the section 1123 of the second tab winding portion 1122 of the second tab 112b, but not to the first tab winding portion 1121 of the second tab 112b.

[0410] 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.

[0411] 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.

[0412] 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.

[0413] 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.

[0414] 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 structure of the battery device.

[0415] 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.

[0416] 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.

[0417] 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.

[0418] In some embodiments, the second end wall 20a is welded to the second current collector 40b to form a third welded portion W3.

[0419] In some embodiments, a pressure relief portion 61 is provided on the second end wall 20a.

[0420] 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.

[0421] 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.

[0422] In some embodiments, the first electrode 112a is a positive electrode and the second electrode 112b is a negative electrode.

[0423] 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.

[0424] In some embodiments, the positive electrode 11a includes an insulating layer 113. At least a portion of the insulating layer 113 is disposed on the end region of the tab 112 near the electrode body 111 in the Z-axis direction. The region of the tab 112 of the positive electrode 11a away from the electrode body 111 is not provided with the insulating layer 113. The insulating layer 113 may be integrally disposed on the tab 112 or may be partially disposed on the tab 112.

[0425] 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.

[0426] 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.

[0427] 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.

[0428] 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.

[0429] 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.

[0430] 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.

[0431] 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.

[0432] 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.

[0433] 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.

[0434] 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.

[0435] 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.

[0436] 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.

[0437] 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.

[0438] The height of the outer casing 20 can be the dimension of the outer casing 20 along the axial direction Z.

[0439] Optionally, the height of the housing 20 is 60mm-100mm.

[0440] 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.

[0441] 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.

[0442] 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.

[0443] 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.

[0444] 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.

[0445] 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.

[0446] 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.

[0447] In some embodiments, the height of the housing 20 is 1.5 to 2.5 times the diameter of the housing 20.

[0448] In some embodiments, the sidewall 212 is made of steel.

[0449] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.5 mm.

[0450] 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.

[0451] 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.

[0452] As an example, the material of sidewall 212 includes stainless steel.

[0453] In some embodiments, the thickness of the sidewall 212 is 0.3 mm to 1.2 mm.

[0454] 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.

[0455] In some embodiments, the material of the first end wall 211 is the same as the material of the side wall 212.

[0456] In some embodiments, the end cap 22 is made of steel.

[0457] Figure 18 is a partial cross-sectional view of a cylindrical battery cell provided in some other embodiments of this application; Figure 19 is an enlarged view of Figure 18 at the boxed area; Figure 20 is a schematic diagram of the current collector of a cylindrical battery cell provided in some embodiments of this application.

[0458] Referring to Figures 18 to 20, 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.

[0459] 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 10.

[0460] 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.

[0461] 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.

[0462] 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.

[0463] 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.

[0464] In some embodiments, the plurality of guide portions 42 are arranged radially.

[0465] In some embodiments, the guide portions 42 are arranged at uniform intervals along the circumference of the flow collector 40.

[0466] In some embodiments, a first weld portion W1 is disposed between two adjacent guide portions 42 in the circumferential direction 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.

[0467] 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.

[0468] 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.

[0469] In some embodiments, the guide portion 42 extends radially R along the electrode assembly 10.

[0470] 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.

[0471] 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.

[0472] 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.

[0473] In some embodiments, there are multiple second recesses 43. The multiple second recesses 43 are arranged at circumferential intervals along the collecting member 40.

[0474] 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.

[0475] 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.

[0476] Optionally, the first current collector 40a is not provided with a guide part 42.

[0477] Figure 21 is a partial cross-sectional schematic diagram of a cylindrical battery cell provided in some other embodiments of this application.

[0478] Referring to Figure 21, the side wall 212 is provided with an inwardly protruding protrusion 2121, and the second current collecting member 40b is connected to the protrusion 2121.

[0479] For example, the protrusion 2121 can be a solid structure or a hollow structure.

[0480] 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.

[0481] 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.

[0482] 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.

[0483] 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.

[0484] 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.

[0485] 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.

[0486] In some embodiments, the second current collector 40b is welded to the protrusion 2121.

[0487] 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.

[0488] 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.

[0489] 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.

[0490] 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.

[0491] In some embodiments, a portion of the insulating member 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.

[0492] 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.

[0493] 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.

[0494] Referring to Figures 4 to 17, this application embodiment provides a cylindrical battery cell 7, which includes a housing 20, an electrode assembly 10, and two current collectors 40. The electrode assembly 10 and the current collectors 40 are disposed within the housing 20.

[0495] 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.

[0496] 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.

[0497] 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.

[0498] 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.

[0499] 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.

[0500] The tab 112 includes a plurality of segments 1123 distributed along the winding direction V of the electrode assembly 10. Along the winding direction V, a cut-off groove 1124 is provided between any two adjacent segments 1123. Each segment 1123 includes a bent section 11231, which includes the end face of the segment 1123 away from the electrode body 111. The bent section 11231 is bent relative to the electrode body 111 in a direction close to the central axis P5 of the cylindrical battery cell 7.

[0501] Each segment 1123 has a connecting end face 1123a oriented along the axial direction Z toward the electrode body 111, and the dimension of the connecting end face 1123a along the winding direction V is L1; in the projection plane perpendicular to the axial direction Z, the straight distance between the orthographic projections of the two ends of the connecting end face 1123a along the winding direction V is L2.

[0502] Multiple segments 1123 consist of at least two first segments 1126 and one second segment 1127. The first segment 1126 satisfies: 95% ≤ L2 / L1 ≤ 99.5%. Along the winding direction V, the segment 1123 furthest from the winding start end E1 is the second segment 1127. The second segment 1127 is wound at least one turn.

[0503] The current collector 40 is disposed on the side of the tab 112 away from the electrode body 111, and at least a portion of the bent sections 11231 of the plurality of segments 1123 are welded to the current collector 40.

[0504] Example

[0505] The following embodiments describe the contents disclosed in this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosures in this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0506] Example 1

[0507] 1. Preparation of positive electrode sheet

[0508] The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is located on both sides of the positive current collector. The positive current collector is an aluminum foil. The positive active material layer is a film layer formed by uniformly coating the positive current collector aluminum foil with a positive slurry (solvent is N-methylpyrrolidone NMP) and then drying and cold pressing it. The positive active material layer includes positive active material, conductive agent carbon black (Super P), and binder polyvinylidene fluoride (PVDF) in a weight ratio of 97:1:2.

[0509] Positive electrode active materials include those with the molecular formula LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Layered transition metal oxides.

[0510] The portion of the positive current collector not covered by the positive active material layer is cut off to form a cut-off piece and a cut-off groove. The total length of the positive current collector is 5000 mm, the number of cut-off pieces is 430, and the total length of the connecting end faces of all cut-off pieces is 3500 mm. The last cut-off piece of the positive electrode is wound twice. The dimensions of each cut-off piece are set according to its position so that all cut-off pieces except the last one satisfy L2 / L1 = 0.95.

[0511] 2. Preparation of negative electrode sheet

[0512] The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is located on both sides of the negative current collector. The negative current collector is a copper foil. The negative active material layer is a film layer formed by uniformly coating the surface of the negative current collector copper foil with negative slurry (solvent is deionized water), and then drying and cold pressing. The negative active material layer includes silicon-based materials (specifically silicon oxide compounds), graphite, conductive carbon black, conductive carbon nanotubes, and binder polyacrylic acid in a weight ratio of 12.6:82.4:1.9:0.1:3.

[0513] The portion of the negative electrode current collector not covered by the negative electrode active material layer is removed to form a cut-off piece and a cut-off groove. The total length of the negative electrode current collector is 5100 mm, the number of cut-off pieces is 435, and the total length of the connecting end faces of the cut-off pieces is 3550 mm. The last cut-off piece of the negative electrode is wound twice. The dimensions of each cut-off piece are set according to its position so that all cut-off pieces except the last one satisfy L2 / L1 = 0.95.

[0514] 3. Isolation components

[0515] We provide PE (polyethylene) based films.

[0516] 4. Preparation of electrolyte

[0517] The electrolyte consists of an organic solvent and a lithium salt. Ethyl carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0518] 5. Preparation of cylindrical battery cells

[0519] Stack the positive electrode, separator, and negative electrode in sequence, with the separator positioned between the positive and negative electrode to provide isolation. Wind the positive electrode, separator, and negative electrode to obtain the electrode assembly. Flatten the section of the positive electrode so that it bends towards the center, and flatten the section of the negative electrode so that it bends towards the center.

[0520] The positive electrode section and the negative electrode section are welded to the two current collector components respectively;

[0521] The electrode assembly is placed inside a cylindrical shell, dried, and then injected with electrolyte. After welding, formation, and aging processes, a cylindrical battery cell is obtained. The electrode assembly and the shell are both cylindrical, comprising a housing and end caps. The housing includes integrally formed sidewalls and end walls, with the sidewalls surrounding the electrode assembly. The end caps and end walls are axially aligned with the housing. The cylindrical battery cell has a diameter of 46 mm and a height of 95 mm.

[0522] Examples 2 to 10

[0523] Battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 was that the cross-section and size of the positive electrode sheet and the number and size of the negative electrode sheet cross-sections were adjusted. The total length of the connecting end faces of all cross-sections of the positive electrode sheet remained unchanged, as did the total length of the connecting end faces of all cross-sections of the negative electrode sheet. See Table 1 for details.

[0524] Performance testing

[0525] 1. DC internal resistance (DCR) test of individual battery cells

[0526] You can refer to the methods in GB / T 31467 "Performance Test Specification for High-Power Lithium-ion Power Batteries for HEVs".

[0527] For example, at 25°C, charge a single battery cell to 4.25V with a constant current of 0.33C, let it stand for 1 minute, then charge it to 4.25V with a constant current of 0.1C, let it stand for 30 minutes, and then discharge it to 2.5V with a constant current of 0.33C. Record the discharge capacity A0 at this point in Ah. Then charge it to 0.5A0Ah with a constant current of 0.33C and adjust the SOC to 50%.

[0528] After placing the battery cell at 25°C for 2 hours, it was discharged at a constant current of 2C for 10 seconds, and ΔU was recorded. 放电 ΔI 放电 The discharge DCR data of lithium-ion batteries can be calculated using the following formula, R. 放电 =ΔU 放电 / ΔI 放电 ,

[0529] Where, ΔU 放电 ΔI represents the voltage change within 10 seconds of the start of discharge. 放电 This indicates the current value within 10 seconds of the start of discharge.

[0530] Table 1

[0531] Referring to Table 1, by setting the cutting groove, the size of a single segment along the winding direction can be reduced, the binding force between segments can be reduced, which is beneficial to the directional bending of the bending section. This can improve the flatness of the surface of the tab opposite to the current collector, reduce the risk of poor soldering between the tab and the current collector, reduce the resistance of the cylindrical battery cell, and improve the cycle performance of the cylindrical battery cell.

[0532] Ensuring that most of the positive electrode segments meet the requirement of 95% ≤ L2 / L1 ≤ 99.5% can reduce the resistance of the cylindrical battery cell and improve its cycle performance. Similarly, ensuring that most of the negative electrode segments meet the requirement of 95% ≤ L2 / L1 ≤ 99.5% can reduce the resistance of the cylindrical battery cell and improve its cycle performance.

[0533] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0534] 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 a housing, an electrode assembly, and a current collector, wherein at least a portion of the electrode assembly and at least a portion of the current collector are disposed within the housing; The electrode assembly is a wound structure and includes two electrodes with opposite polarities. At least one of the electrodes includes an electrode body and a tab arranged along the axial direction of the cylindrical battery cell. 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 the active material layer. 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. Each of the segments includes a bent section, the bent section including an end face of the segment away from the electrode body, the bent section being bent relative to the electrode body toward a direction close to the central axis of the cylindrical battery cell; The current collector is disposed on the side of the electrode tab away from the electrode body, and at least a portion of the bent sections of the plurality of segments are welded to the current collector.

2. The cylindrical battery cell according to claim 1, wherein, Each of the segments has a connecting end face facing the electrode body along the axial direction, the dimension of the connecting end face along the winding direction being L1; in a projection plane perpendicular to the axial direction, the straight-line distance between the orthographic projections of the two ends of the connecting end face along the winding direction is L2; At least a portion of the plurality of slices satisfy the following condition: 95% ≤ L2 / L1 ≤ 99.5%.

3. The cylindrical battery cell according to claim 2, wherein, At least a portion of the plurality of slices satisfy the following condition: 96% ≤ L2 / L1 ≤ 99%.

4. The cylindrical battery cell according to claim 2 or 3, wherein, The plurality of slices includes at least two first slices, wherein the first slices satisfy: 95% ≤ L2 / L1 ≤ 99.5%; The current collection component is welded to the first section.

5. The cylindrical battery cell according to any one of claims 2-4, wherein, The plurality of slices includes a first slice, which satisfies: 95% ≤ L2 / L1 ≤ 99.5%; The ratio of the number of the first slices to the total number of slices is greater than or equal to 80%.

6. The cylindrical battery cell according to claim 4 or 5, wherein, The electrode sheet has a winding start end and a winding end end at its two ends along the winding direction; 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 plurality of segments includes at least one second segment, the second segment being wound at least one turn; along the winding direction, the segment farthest from the starting end of the winding is the second segment.

7. The cylindrical battery cell according to claim 6, wherein, The plurality of slices consists of a plurality of first slices and a second slice.

8. The cylindrical battery cell according to claim 6 or 7, wherein, The current collecting component is not welded to the second section.

9. The cylindrical battery cell according to any one of claims 1-8, wherein, Each of the said segments has a connecting end face that faces the electrode body along the said axial direction; Along the axial direction, the connecting end face is spaced apart from the bent section.

10. The cylindrical battery cell according to any one of claims 1-9, wherein, The electrode sheet has a winding start end and a winding end end at its two ends along the winding direction; 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 plurality of segments includes at least one second segment, the second segment being wound at least one turn; along the winding direction, the segment farthest from the starting end of the winding is the second segment.

11. The cylindrical battery cell according to claim 10, wherein, Along the winding direction, the second section is wound with a number of turns less than or equal to 5.

12. The cylindrical battery cell according to claim 10 or 11, wherein, In a projection plane perpendicular to the axis, the orthographic projection of the current collecting member does not overlap with the orthographic projection of the second segment.

13. The cylindrical battery cell according to any one of claims 1-12, wherein, The electrode tab also 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 adjacent segments along the winding direction form the cut-off groove, and the bottom surface of the cut-off groove is formed on one side edge of the transition connection portion for connecting the segments.

14. The cylindrical battery cell according to claim 13, wherein, Each of the segments has a connecting end face connected to the transition connection portion, and the dimension of the connecting end face along the winding direction is L1; The sum of the dimensions of the transition connection and the segment in the axial direction is L3, and 0.01≤L3 / L1≤0.

3.

15. The cylindrical battery cell according to claim 13 or 14, wherein, The dimension of the transition connection in the axial direction is L4, where 0.1mm≤L4≤2mm.

16. The cylindrical battery cell according to any one of claims 13-15, wherein, At least one of the electrodes includes a positive electrode, the positive electrode includes the electrode body, the tab and the insulating layer, the tab and the transition connection portion of the positive electrode are not coated with the active material layer, and the insulating layer is disposed on the transition connection portion.

17. The cylindrical battery cell according to any one of claims 1-16, 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.

18. The cylindrical battery cell according to any one of claims 1-17, wherein, Along the axial direction, the size of the truncated piece decreases in the direction away from the electrode body.

19. The cylindrical battery cell according to any one of claims 1-18, wherein, In the radial direction of the electrode assembly, the size of the bent section of the slab is greater than or equal to 2 mm.

20. The cylindrical battery cell according to any one of claims 1-19, wherein, The bent segments of the plurality of slices form an overlapping area; At least a portion of the overlapping region has a dimension greater than or equal to 100 μm in the axial direction, and the portion of the overlapping region with a dimension greater than or equal to 100 μm in the axial direction is welded to the current collector.

21. The cylindrical battery cell according to any one of claims 1-20, wherein, The electrode ear includes a first electrode ear winding portion and a second electrode ear winding portion located outside the first electrode ear winding portion; The plurality of segments are formed in the second electrode ear winding portion; In the axial direction, the truncated piece extends beyond the first electrode lug winding portion in a direction away from the electrode body; The current collector is not welded to the first electrode ear winding portion.

22. The cylindrical battery cell according to claim 21, wherein, In the winding direction, the length of the second electrode ear winding portion is greater than the length of the first electrode ear winding portion.

23. The cylindrical battery cell according to claim 21 or 22, 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; The portion of the electrode tab near the starting end of winding is provided with a first notch; along the winding direction, the first notch is located on the side of the plurality of segments near the starting end of winding; along the direction from the electrode body to the electrode tab, the first notch is located on the side of the winding portion of the first electrode tab.

24. The cylindrical battery cell according to any one of claims 21-23, 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, 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.

25. The cylindrical battery cell according to any one of claims 21-24, wherein, The housing is provided with a pressure relief portion at at least one end along the axial direction, and on a projection plane perpendicular to the axial direction, the orthographic projection of the first electrode ear winding portion is located within the orthographic projection of the pressure relief portion.

26. The cylindrical battery cell according to claim 25, wherein, The electrode includes a first electrode winding portion, and the first electrode ear winding portion is formed in a part of the first electrode winding portion; On a projection plane perpendicular to the axis, the orthographic projection of the first electrode winding portion is located within the orthographic projection of the pressure relief portion, which is configured to at least partially open and form an exhaust channel during pressure relief, through which at least a portion of the first electrode winding portion is discharged to the outside of the housing.

27. The cylindrical battery cell according to claim 25 or 26, 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.

28. The cylindrical battery cell according to any one of claims 25-27, wherein, 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.

29. The cylindrical battery cell according to any one of claims 21-28, wherein, At least a portion of the bent sections of the plurality of segments are welded to the current collecting member to form a first welded portion; On the projection plane perpendicular to the axis, the two ends of the orthographic projection of the first welded part have a first projection endpoint and a second projection endpoint, respectively. The first projection endpoint is closer to the central axis of the cylindrical battery cell than the second projection endpoint. The area between the first arc line that passes through the first projection endpoint and surrounds the first electrode winding part and the second arc line that passes through the second projection endpoint and surrounds the first electrode winding part is the first transverse area. At least some of the cut-off slots form a first group of cut-off slots, in which the orthographic projection of the bottom surface of all the cut-off slots lies within the first transverse region; Wherein, in the first group of cut-off slots, the number of turns of a single cut-off slot is ≤3; and / or, in the first group of cut-off slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

30. The cylindrical battery cell according to any one of claims 21-29, comprising an electrode terminal disposed on the housing, the electrode terminal being welded to the current collector to form a second welded portion; On the projection plane perpendicular to the axial direction, the two ends of the orthographic projection of the second weld portion have a third projection endpoint and a fourth projection endpoint, respectively. The third projection endpoint is closer to the 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 ear winding portion and the fourth arc line that passes through the fourth projection endpoint and surrounds the first electrode ear winding 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. in, In the second set of cut-off slots, the number of turns of a single cut-off slot is ≤3; and / or, in the second set of cut-off slots, the number of cut-off slots that are radially opposite and interconnected along the electrode assembly is ≤3.

31. The cylindrical battery cell according to any one of claims 1-30, 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, and the first electrode tab and the second electrode tab are respectively disposed at opposite ends of the electrode body along the axial direction; Along the axial direction, both ends of the electrode assembly are provided with current collectors, and the current collectors at both ends of the electrode assembly are respectively a first current collector and a second current collector; the first current collector is welded to the segment of the first electrode tab; the second current collector is welded to the segment of the second electrode tab.

32. The cylindrical battery cell according to claim 31, 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.

33. The cylindrical battery cell according to claim 32, wherein, The second end wall is welded to the second current collector, and the second end wall is electrically connected to the side wall.

34. The cylindrical battery cell according to claim 32, wherein, The sidewall is provided with an inwardly protruding part, and the second current collecting member is connected to the protruding part.

35. The cylindrical battery cell according to claim 34, 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.

36. A battery device comprising a plurality of cylindrical battery cells according to any one of claims 1-35.

37. An electrical device comprising a battery device according to claim 36, the battery device being used to provide electrical energy.

Images