Battery cell and electric device

Abstract

A battery cell and an electric device. The battery cell comprises an electrode assembly, a tab and a tab lead. The tab comprises a plurality of tab units. One end of the plurality of tab units is arranged at intervals in a first direction and is connected to the side of the electrode assembly in a second direction. The other ends of the plurality of tab units converge and form a root portion, a first connecting portion, a first extending portion, a second connecting portion and a second extending portion, which are sequentially connected to each other. The root portion, the first extending portion and the second extending portion are sequentially arranged at intervals on one side of the electrode assembly in the second direction, and the first connecting portion and the second connecting portion are respectively bent. The plurality of tab units are connected to each other and are provided with a first weld mark, one end of the first weld mark being located at the root portion, and the other end of the first weld mark extending to the first extending portion through the first connecting portion. The second direction is perpendicular to the first direction. Part of the tab lead and the second extending portion overlap in the second direction, and the overlapping region between the tab lead and the second extending portion is provided with a second weld mark. The battery cell is beneficial for improving the energy density.

Description

Battery cells and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 28, 2023, with application number CN202311843801.X and titled “Battery Cells and Electrical Equipment.” Technical Field

[0002] The present application relates to the field of energy storage technology, and in particular to a battery cell and electrical equipment. Background Art

[0003] In existing battery cells, as shown in Figure 1, a roller weld mark 91 is provided at the connection between the tab and the electrode assembly, and a transfer weld mark 92 is provided at the connection between the tab and the tab lead. One end of roller weld mark 91 is adjacent to the electrode assembly, while the other end of roller weld mark 91 is bent and spaced apart from transfer weld mark 92 along the thickness of the battery cell. The tab segment between roller weld mark 91 and transfer weld mark 92 is used to reserve spacing to reduce the risk of interference between roller weld mark 91 and transfer weld mark 92.

[0004] Since the tab segment between the roller-stamped weld mark 91 and the transfer weld mark 92 extends along the thickness direction of the battery cell, and in the thickness direction of the battery cell, there is no space of common height between the bending part of the roller-stamped weld mark 91 and the part of the tab lead located outside the transfer weld mark 92, the tab and the tab lead will occupy a large space in the thickness direction of the battery cell, which is not conducive to improving the energy density of the battery cell. Summary of the Invention

[0005] In view of the above situation, it is necessary to provide a battery cell that is conducive to improving the energy density of the battery cell.

[0006] An embodiment of the present application provides a battery cell, which includes an electrode assembly, a tab and a tab lead. The tab includes a plurality of tab units, one end of each of which is arranged along a first direction and is respectively connected to one side of the electrode assembly in a second direction, and the other ends of each of the tab units are gathered together to form a root, a first connection portion, a first extension portion, a second connection portion and a second extension portion that are connected in sequence. The root portion, the first extension portion and the second extension portion are arranged in sequence on one side of the electrode assembly along the second direction, and the first connection portion and the second connection portion are bent respectively. The plurality of tab units are interconnected and provided with a first weld mark, one end of the first weld mark is located at the root portion, and the other end of the first weld mark extends to the first extension portion through the first connection portion. The first direction is the thickness direction of the electrode assembly, and the second direction is perpendicular to the first direction. Part of the tab lead and the second extension portion overlap in the second direction, and a second weld mark is provided in the overlapping area of ​​the tab lead and the second extension portion.

[0007] In the above-mentioned battery cell, the first extension portion and the second extension portion are arranged sequentially along the second direction on one side of the electrode assembly, the first connection portion and the second connection portion are respectively bent, one end of the first weld mark is located at the root, the other end of the first weld mark extends through the first connection portion to the first extension portion, and the second weld mark is arranged on the second extension portion. This arrangement allows the tab segment located between the first weld mark and the second weld mark to extend along the bending direction of the second connection portion, while ensuring the reserved spacing between the first weld mark and the second weld mark, while also shortening the height occupied by the tab segment in the first direction. Furthermore, it also facilitates the existence of a space of the same height in the first direction between the bending portion of the first weld mark (i.e., the portion of the first weld mark located at the first connection portion) and the portion of the tab lead located outside the second weld mark. This is conducive to improving the spatial utilization of the tab and the tab lead in the first direction, thereby increasing the energy density of the battery cell.

[0008] In some embodiments of the present application, along the extension direction of the tab, the spacing S1 between the first and second weld marks satisfies 0.5mm≤S1≤2mm. When S1 is too small (e.g., less than 0.5mm), the first and second weld marks are likely to interfere with each other during welding, affecting welding reliability. When S1 is too large (e.g., greater than 2mm), the tab segment between the first and second weld marks will extend longer, resulting in wasted space. By limiting the spacing to 0.5mm≤S1≤2mm, the risk of interference between the first and second weld marks during welding is reduced, welding reliability is improved, and the space utilization of the tab on one side of the electrode assembly is increased, thereby facilitating increased energy density of the battery cell. Along the second direction, the projection of the first weld mark on the first extension portion and the second weld mark do not overlap, so that the area of ​​the second extension portion not provided with the second weld mark and the first weld mark are arranged opposite each other along the second direction, and the area of ​​the first extension portion not provided with the first weld mark and the second weld mark are arranged opposite each other along the second direction. This helps reduce the risk of interference between the first and second weld marks during welding and improves welding reliability.

[0009] In some embodiments of the present application, along the second direction, the projection of the tab and the projection of the tab lead are respectively located within the projection range of the electrode assembly, so as to reduce the space waste caused by the tab and the tab lead exceeding the electrode assembly in the first direction, thereby facilitating the improvement of the space utilization of the tab and the tab lead in the first direction, and further contributing to the improvement of the energy density of the battery cell.

[0010] In some embodiments of the present application, the tab lead includes a third extension, a third connecting portion, and a fourth extension connected in sequence. The third extension is arranged along the second direction on the side of the second extension facing the electrode assembly, and at least a portion of the third extension overlaps the second extension in the second direction. A second weld mark is provided in the overlapping region of the third extension and the second extension. The third connecting portion is bent to help alleviate the stress of bending the tab lead. The fourth extension extends along the second direction away from the electrode assembly to facilitate electrical connection to an external circuit.

[0011] In some embodiments of the present application, the first extension portion, the second extension portion and the third extension portion respectively extend approximately along the first direction, so that the first extension portion, the second extension portion and the third extension portion are arranged on one side of the electrode assembly along the second direction, which is beneficial for making the bending parts of the tab and the tab lead bear uniform force, thereby reducing the risk of rebound or breakage of the tab and the tab lead.

[0012] In some embodiments of the present application, along the first direction, the thickness H1 of the electrode assembly satisfies: H1 ≤ 3.8 mm. In existing battery cells, since the tab segment between the roller weld mark and the transfer weld mark extends along the thickness direction of the battery cell, and in the thickness direction of the battery cell, there is no space of common height between the bending portion of the roller weld mark and the portion of the tab lead located outside the transfer weld mark, the thickness of the battery cell will be thicker (greater than 3.8 mm). By extending the tab segment between the first weld mark and the second weld mark along the bending direction of the second connection portion, there is a space of common height in the first direction between the bending portion of the first weld mark (i.e., the portion of the first weld mark located at the first connection portion) and the portion of the tab lead located outside the second weld mark, which can reduce the thickness of the battery cell and facilitate miniaturization of the battery cell.

[0013] In some embodiments of the present application, along the first direction, the height H2 from the endpoint where the third connection portion is connected to the third extension portion to the surface of the fourth extension portion away from the third extension portion satisfies the following: 0.5mm≤H2≤0.7mm. When H2 is too small (for example, less than 0.5mm), it is easy for the fourth extension portion to bend around the endpoint where the third connection portion is connected to the third extension portion to have a smaller angle range, making it inconvenient to adjust the angle at which the fourth extension portion is connected to the external circuit; when H2 is too large (for example, greater than 0.7mm), it is easy for the third connection portion and the fourth extension portion to occupy a larger space in the first direction, resulting in space waste. By limiting 0.5mm≤H2≤0.7mm, it is easy to adjust the angle at which the fourth extension portion is connected to the external circuit, and it is easy to improve the space utilization of the third connection portion and the fourth extension portion in the first direction, which is beneficial to improving the energy density of the battery cell.

[0014] In some embodiments of the present application, along the first direction, the height H3 from the endpoint where the third extension portion is connected to the third connecting portion to the surface of the second connecting portion facing away from the second extension portion satisfies the following: 1mm≤H3≤1.5mm. When H3 is too small (e.g., less than 1mm), the overlapping area of ​​the tab lead and the second extension portion is likely to be small, resulting in a lower welding difficulty and connection strength of the second weld mark. When H3 is too large (e.g., greater than 1.5mm), the second connecting portion, the second extension, and the third extension portion may occupy a larger space in the first direction, resulting in space waste. By limiting 1mm≤H3≤1.5mm, the welding difficulty of the second weld mark is reduced and the connection strength of the second weld mark is improved, and the space utilization of the second connecting portion, the second extension, and the third extension portion in the first direction is improved, which is conducive to improving the energy density of the battery cell.

[0015] In some embodiments of the present application, the first extension portion extends along a first direction, and the second and third extension portions extend along the same direction that is inclined relative to the first direction. Along the extension direction of the tab, the extension length W1 from the endpoint where the third extension portion connects to the third connecting portion to the surface of the second connecting portion facing away from the second extension portion, and the inclination angle α between the second and third extension portions relative to the first direction satisfy the following relationship: α>arccos(H3 / W1), so that the fourth extension portion can extend outward along the second direction to connect to an external circuit with the third extension portion tilted, without affecting the battery thickness.

[0016] In some embodiments of the present application, an electrode assembly includes a first electrode sheet, a separator, and a second electrode sheet stacked sequentially along a first direction. The first electrode sheet includes a first current collector, a first active material layer, and a conductive member. The first current collector includes a first segment and a second segment sequentially arranged along a second direction. The first active material layer is connected to the first segment. When viewed along the first direction, one end of the conductive member is connected to the second segment. The other end of the conductive member protrudes from the first current collector in the second direction and is connected to the tab unit.

[0017] In some embodiments of the present application, the first current collector includes a support layer, and a first conductive layer and a second conductive layer disposed on both sides of the support layer in a first direction. The first active material layer is connected to the first conductive layer and / or the second conductive layer located in the first section, and the conductive member is connected to the first conductive layer and / or the second conductive layer located in the second section. When the first current collector is mechanically damaged by an external force, the first conductive layer and the second conductive layer help reduce the generation of metal burrs, thereby reducing the risk of short circuits.

[0018] In some embodiments of the present application, the battery cell further includes an insulating member, one end of the insulating member being bonded to a surface of the first active material layer facing away from the first current collector, and the other end of the insulating member being bonded to a surface of the conductive member facing away from the first current collector. The insulating member is used to improve insulation isolation of the corresponding coverage area from other structural members in the first direction, thereby reducing the risk of short circuits and improving the reliability of the battery cell.

[0019] An embodiment of the present application further provides an electrical device comprising any one of the battery cells in the above embodiments.

[0020] In the above-mentioned battery cell and electrical device, the first extension portion and the second extension portion are arranged sequentially along the second direction on one side of the electrode assembly, the first connection portion and the second connection portion are respectively bent, one end of the first weld mark is located at the root, the other end of the first weld mark extends through the first connection portion to the first extension portion, and the second weld mark is located on the second extension portion. This arrangement allows the tab segment located between the first weld mark and the second weld mark to extend along the bending direction of the second connection portion, thereby shortening the height occupied by the tab segment in the first direction while ensuring the reserved spacing between the first weld mark and the second weld mark. Furthermore, it facilitates the sharing of space at a common height in the first direction between the bent portion of the first weld mark (i.e., the portion of the first weld mark located at the first connection portion) and the portion of the tab lead located outside the second weld mark. This, in turn, helps improve the spatial utilization of the tab and the tab lead in the first direction, thereby increasing the energy density of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of the structure of a battery cell provided by the prior art.

[0022] FIG2 is a schematic diagram of the structure of a battery cell in one embodiment of the present application.

[0023] FIG3 is a schematic structural diagram of a battery cell in another embodiment of the present application.

[0024] FIG4 is a schematic structural diagram of a packaging bag for a battery cell in one embodiment of the present application.

[0025] FIG5 is a schematic structural diagram of an electrode assembly of a battery cell in one embodiment of the present application.

[0026] FIG6 is a schematic structural diagram of a first electrode of a battery cell in one embodiment of the present application.

[0027] FIG7 is a schematic structural diagram of an insulating member of a battery cell in one embodiment of the present application.

[0028] FIG8 is a schematic structural diagram of an electrical device in an embodiment of the present application.

[0029] Description of main component symbols Battery cell 100 Electric device 200 Electrode assembly 10 First pole piece 11 First current collector 111 First section 111a Second section 111b Support layer 1111 First conductive layer 1112 Second conductive layer 1113 First active material layer 112 Conductive member 113 Separator 12 Second pole piece 13

[0030] Tab 20 Tab unit 20a Root 21 First connection portion 22 First extension portion 23 Second connection portion 24 Second extension portion 25 Tab lead 30 End point 301 Third extension portion 31 Third connection portion 32 Fourth extension portion 33 First weld mark 41 Second weld mark 42 Packaging bag 50 Colloid 60 Insulation member 70 First direction Z Second direction X Roller weld mark 91 Transfer weld mark 92

[0031] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0033] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a centrally located element. When an element is considered to be "set" on another element, it can be directly set on the other element or there may be a centrally located element. When a value is considered to be "equal" to another value, it means that the two values ​​are equal within a set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if the values ​​are unequal, they are still judged to be approximately equal. When a value is considered to have a "1:1" ratio with another value, it means that the two values ​​are equal within a set deviation, and the set deviation range is within 5%. In other words, when at least one of the two values ​​fluctuates within the set deviation range, even if the values ​​are unequal, they are still judged to be equal in ratio.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] It should be understood that, considering the factors of actual processing tolerance, the term "perpendicular" in the technical solution of this application is used to describe the ideal state between two components. In the actual production or use state, there may be a state that is approximately perpendicular between the two components. For example, in combination with the numerical description, perpendicularity can refer to the angle between two straight lines being between 90°±10°, perpendicularity can also refer to the dihedral angle between two planes being between 90°±10°, and perpendicularity can also refer to the angle between a straight line and a plane being between 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic point of view, the components can be considered as "straight lines" or "planes" if the overall extension direction is a straight line or a plane.

[0036] An embodiment of the present application provides a battery cell, which includes an electrode assembly, a tab and a tab lead. The tab includes a plurality of tab units, one end of each of which is arranged along a first direction and is respectively connected to one side of the electrode assembly in a second direction, and the other ends of each of the tab units are gathered together to form a root, a first connection portion, a first extension portion, a second connection portion and a second extension portion that are connected in sequence. The root portion, the first extension portion and the second extension portion are arranged in sequence on one side of the electrode assembly along the second direction, and the first connection portion and the second connection portion are bent respectively. The plurality of tab units are interconnected and provided with a first weld mark, one end of the first weld mark is located at the root portion, and the other end of the first weld mark extends to the first extension portion through the first connection portion. The first direction is the thickness direction of the electrode assembly, and the second direction is perpendicular to the first direction. Part of the tab lead and the second extension portion overlap in the second direction, and a second weld mark is provided in the overlapping area of ​​the tab lead and the second extension portion.

[0037] In the above-mentioned battery cell, the first extension portion and the second extension portion are arranged sequentially along the second direction on one side of the electrode assembly, the first connection portion and the second connection portion are respectively bent, one end of the first weld mark is located at the root, the other end of the first weld mark extends through the first connection portion to the first extension portion, and the second weld mark is arranged on the second extension portion. This arrangement allows the tab segment located between the first weld mark and the second weld mark to extend along the bending direction of the second connection portion, while ensuring the reserved spacing between the first weld mark and the second weld mark, while also shortening the height occupied by the tab segment in the first direction. Furthermore, it also facilitates the existence of a space of the same height in the first direction between the bending portion of the first weld mark (i.e., the portion of the first weld mark located at the first connection portion) and the portion of the tab lead located outside the second weld mark. This is conducive to improving the spatial utilization of the tab and the tab lead in the first direction, thereby increasing the energy density of the battery cell.

[0038] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0039] 2 , an embodiment of the present application provides a battery cell 100. The battery cell 100 may be used in, but is not limited to, a secondary battery. A secondary battery is a battery that can be recharged to activate active materials after discharge and continue to be used.

[0040] The battery cell 100 includes an electrode assembly 10, a tab 20, and a tab lead 30. The electrode assembly 10 is used to convert chemical energy into electrical energy. The electrode assembly 10 includes a positive electrode sheet, a separator, and a negative electrode sheet, which are arranged in sequence. Optionally, the positive electrode sheet, separator, and negative electrode sheet are wound or laminated.

[0041] The tab 20 includes a plurality of tab units 20 a , and the plurality of tab units 20 a have the same polarity, that is, the plurality of tab units 20 a are all connected to the positive electrode sheet, or the plurality of tab units 20 a are all connected to the negative electrode sheet.

[0042] One end of the plurality of tab units 20a is spaced apart along a first direction Z and is respectively connected to one side of the electrode assembly 10 in a second direction X. The first direction Z is the thickness direction of the electrode assembly 10, and the second direction X is perpendicular to the first direction Z. The other ends of the plurality of tab units 20a are gathered together to form a root portion 21, a first connecting portion 22, a first extending portion 23, a second connecting portion 24, and a second extending portion 25 that are connected in sequence, so as to facilitate cutting and shaping of the tabs 20 during the manufacturing process.

[0043] The root portion 21, the first extension portion 23, and the second extension portion 25 are arranged in sequence on one side of the electrode assembly 10 along the second direction X. The first connecting portion 22 and the second connecting portion 24 are bent so that the root portion 21, the first connecting portion 22, and the first extension portion 23 form a U-shaped structure, and the first extension portion 23, the second connecting portion 24, and the second extension portion 25 form a U-shaped structure, with the openings of the two U-shaped structures facing opposite directions. The first connecting portion 22 is used to form an arc transition between the root portion 21 and the first extension portion 23, and the second connecting portion 24 is used to form an arc transition between the first extension portion 23 and the second extension portion 25, which helps to relieve the stress caused by the bending of the tab 20.

[0044] Multiple tab units 20a are interconnected and provided with a first weld mark 41. One end of the first weld mark 41 is located at the root portion 21, and the other end of the first weld mark 41 extends through the first connecting portion 22 to the first extending portion 23. The first weld mark 41 is used to improve the structural stability of the tab 20. Specifically, the first weld mark 41 is formed by roller welding.

[0045] Part of the tab lead 30 and the second extension 25 overlap in the second direction X. A second weld mark 42 is provided in the overlapping region of the tab lead 30 and the second extension 25. The second weld mark 42 is used to enhance the connection strength between the tab lead 30 and the second extension 25. Specifically, the second weld mark 42 is formed by transfer welding. The portion of the tab lead 30 outside the second weld mark 42 is used for electrical connection to an external circuit.

[0046] In the battery cell 100 described above, the first extension portion 23 and the second extension portion 25 are arranged sequentially along the second direction X on one side of the electrode assembly 10. The first connection portion 22 and the second connection portion 24 are bent, respectively. One end of the first weld mark 41 is located at the root portion 21, and the other end of the first weld mark 41 extends through the first connection portion 22 to the first extension portion 23. The second weld mark 42 is located on the second extension portion 25. This arrangement allows the tab segment located between the first weld mark 41 and the second weld mark 42 to extend along the bending direction of the second connection portion 24. This arrangement reduces the height of the tab segment in the first direction Z while ensuring the reserved spacing between the first weld mark 41 and the second weld mark 42. Furthermore, this arrangement allows the bent portion of the first weld mark 41 (i.e., the portion of the first weld mark located at the first connection portion 22) and the portion of the tab lead 30 located outside the second weld mark 42 to share a common height in the first direction Z. This, in turn, improves the space utilization of the tab 20 and the tab lead 30 in the first direction Z, thereby increasing the energy density of the battery cell 100.

[0047] Continuing with FIG. 2 , in some embodiments, along the extension direction of the tab 20 , the spacing S1 between the first weld mark 41 and the second weld mark 42 (i.e., the extension length of the tab segment between the first weld mark 41 and the second weld mark 42) satisfies 0.5 mm ≤ S1 ≤ 2 mm. When S1 is too small (e.g., less than 0.5 mm), the first weld mark 41 and the second weld mark 42 may interfere with each other during welding, affecting welding reliability. When S1 is too large (e.g., greater than 2 mm), the extension length of the tab segment between the first weld mark 41 and the second weld mark 42 may be longer, resulting in wasted space. By limiting the spacing to 0.5 mm ≤ S1 ≤ 2 mm, the risk of interference between the first weld mark 41 and the second weld mark 42 during welding is reduced, welding reliability is improved, and the space utilization of the tab 20 on one side of the electrode assembly 10 is increased, thereby facilitating an increase in the energy density of the battery cell 100.

[0048] Optionally, S1 may be 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, or any other value within the range of 0.5 mm ≤ S1 ≤ 2 mm.

[0049] Furthermore, 0.5mm≤S1≤0.65mm can further reduce the risk of interference between the first weld mark 41 and the second weld mark 42 during the welding process, improve the reliability of welding, and facilitate improving the space utilization of the tab 20 on one side of the electrode assembly 10, thereby facilitating the improvement of the energy density of the battery cell 100.

[0050] In some embodiments, along the second direction X, there is no overlapping area between the projection of the first weld mark 41 located on the first extension portion 23 and the second weld mark 42, so that the area of ​​the second extension portion 25 where the second weld mark 42 is not provided and the first weld mark 41 are arranged relative to each other along the second direction X, and the area of ​​the first extension portion 23 where the first weld mark 41 is not provided and the second weld mark 42 are arranged relative to each other along the second direction X, which is beneficial to reducing the risk of interference between the first weld mark 41 and the second weld mark 42 during the welding process and improving the reliability of welding.

[0051] In some embodiments, along the first direction Z, the projection of the first weld mark 41 located on the first extension portion 23 partially overlaps with the projection of the second weld mark 42, so as to reduce the space occupied by the first weld mark 41 and the second weld mark 42 in the second direction X, thereby facilitating the improvement of the energy density of the battery cell 100.

[0052] Please continue to refer to Figure 2. In some embodiments, along the second direction X, the projection of the tab 20 and the projection of the tab lead 30 are respectively located within the projection range of the electrode assembly 10, so as to reduce the space waste caused by the tab 20 and the tab lead 30 exceeding the electrode assembly 10 in the first direction Z, thereby facilitating the improvement of the space utilization of the tab 20 and the tab lead 30 in the first direction Z, and further contributing to the improvement of the energy density of the battery cell 100.

[0053] Continuing with FIG. 2 , in some embodiments, the tab lead 30 includes a third extension portion 31, a third connection portion 32, and a fourth extension portion 33, which are sequentially connected. The third extension portion 31 is arranged along the second direction X on the side of the second extension portion 25 facing the electrode assembly 10. At least a portion of the third extension portion 31 and the second extension portion 25 overlap in the second direction X, and a second weld mark 42 is provided in the overlapping region of the third extension portion 31 and the second extension portion 25. The third connection portion 32 is bent and configured to form an arc transition between the third extension portion 31 and the fourth extension portion 33, thereby relieving stress caused by the bending of the tab lead 30. The fourth extension portion 33 extends away from the electrode assembly 10 along the second direction X to facilitate electrical connection to an external circuit.

[0054] In some embodiments, the first extension portion 23, the second extension portion 25 and the third extension portion 31 respectively extend approximately along the first direction Z, so that the first extension portion 23, the second extension portion 25 and the third extension portion 31 are arranged on one side of the electrode assembly 10 along the second direction X, which is beneficial for making the bending parts of the tab 20 and the tab lead 30 evenly stressed, thereby reducing the risk of rebound or breakage of the tab 20 and the tab lead 30.

[0055] It should be noted that extending substantially along the first direction Z means that the angle between the extending direction and the first direction Z is within a range of 180°±10°. In some embodiments, the root portion 21 extends substantially along the first direction Z, which helps to evenly apply force to each bending portion of the tab unit 20a, thereby reducing the risk of rebound or breakage of the tab 20.

[0056] 3 , it can be understood that in other embodiments, at least one of the first extension portion 23 , the second extension portion 25 and the third extension portion 31 is tilted relative to the first direction Z to facilitate adaptation to the spacing between the electrode assembly 10 and the external circuit.

[0057] Referring again to FIG. 2 , in some embodiments, along the first direction Z, the thickness H1 of the electrode assembly 10 satisfies: H1 ≤ 3.8 mm. In existing battery cells, because the tab segment between the roller weld mark and the transfer weld mark extends along the thickness direction of the battery cell, and there is no shared height space between the bend of the roller weld mark and the portion of the tab lead located outside the transfer weld mark in the thickness direction of the battery cell, the battery cell thickness can be relatively thick (greater than 3.8 mm). In the present application, by extending the tab segment between the first weld mark 41 and the second weld mark 42 along the bending direction of the second connection portion 24, a shared height space is created in the first direction Z between the bend of the first weld mark 41 (i.e., the portion of the first weld mark located on the first connection portion 22) and the portion of the tab lead 30 located outside the second weld mark 42. This can reduce the thickness of the battery cell 100, making H1 ≤ 3.8 mm, and facilitates miniaturization of the battery cell 100.

[0058] Furthermore, 2.5 mm ≤ H1 ≤ 3.8 mm, so as to reserve space for arranging the tab 20 and the tab lead 30 in the first direction Z, and is conducive to miniaturization of the battery cell 100 .

[0059] Optionally, H1 may be 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, or any other value within the range of H1 ≥ 2.5 mm.

[0060] In some embodiments, along the first direction Z, the height H2 from the endpoint 301 where the third connecting portion 32 connects to the third extension portion 31 to the surface of the fourth extension portion 33 facing away from the third extension portion 31 satisfies the following: 0.5 mm ≤ H2 ≤ 0.7 mm. If H2 is too small (e.g., less than 0.5 mm), the fourth extension portion 33 may bend around the endpoint 301 where the third connecting portion 32 connects to the third extension portion 31 over a narrow range, making it difficult to adjust the angle at which the fourth extension portion 33 connects to the external circuit. If H2 is too large (e.g., greater than 0.7 mm), the third connecting portion 32 and the fourth extension portion 33 may occupy a large space in the first direction Z, resulting in wasted space. By limiting the height H2 to 0.5 mm ≤ H2 ≤ 0.7 mm, the angle at which the fourth extension portion 33 connects to the external circuit can be adjusted, and the space utilization of the third connecting portion 32 and the fourth extension portion 33 in the first direction Z can be improved, thereby facilitating an increase in the energy density of the battery cell 100.

[0061] Optionally, H2 can be 0.5mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, 0.55mm, 0.56mm, 0.57mm, 0.58mm, 0.59mm, 0.6mm, 0.61mm, 0.62mm, 0.63mm, 0.64mm, 0.65mm, 0.66mm, 0.67mm, 0.68mm, 0.69mm, 0.7mm, and any other value in the range of 0.5mm≤H2≤0.7mm.

[0062] Furthermore, 0.58mm≤H2≤0.62mm, so as to further facilitate the adjustment of the angle of connection between the fourth extension portion 33 and the external circuit, and to facilitate the improvement of the space utilization of the third connection portion 32 and the fourth extension portion 33 in the first direction Z, thereby facilitating the improvement of the energy density of the battery cell 100.

[0063] In some embodiments, along the first direction Z, the height H3 from the endpoint 301 where the third extension 31 connects to the third connection portion 32 to the surface of the second connection portion 24 facing away from the second extension 25 satisfies the following: 1 mm ≤ H3 ≤ 1.5 mm. When H3 is too small (e.g., less than 1 mm), the overlapping area between the tab lead 30 and the second extension 25 is likely to be small, resulting in difficulty in welding the second weld mark 42 and lower connection strength. When H3 is too large (e.g., greater than 1.5 mm), the second connection portion 24, the second extension 25, and the third extension 31 may occupy a large space in the first direction Z, resulting in wasted space. By limiting the requirement of 1 mm ≤ H3 ≤ 1.5 mm, the difficulty in welding the second weld mark 42 is reduced, the connection strength of the second weld mark 42 is improved, and the space utilization of the second connection portion 24, the second extension 25, and the third extension 31 in the first direction Z is improved, thereby facilitating an increase in the energy density of the battery cell 100.

[0064] Optionally, H3 may be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, or any other value within the range of 1 mm ≤ H3 ≤ 1.5 mm.

[0065] Furthermore, 1.1 mm ≤ H3 ≤ 1.3 mm, so as to further reduce the welding difficulty of the second weld mark 42 and improve the connection strength of the second weld mark 42, and facilitate improving the space utilization of the second connection portion 24, the second extension portion 25 and the third extension portion 31 in the first direction Z, thereby facilitating improving the energy density of the battery cell 100.

[0066] Please refer to Figure 3 again. In some embodiments, the first extension portion 23 extends along the first direction Z, the second extension portion 25 and the third extension portion 31 both extend in the same direction inclined relative to the first direction Z, and along the extension direction of the tab 20, the extension length W1 from the endpoint 301 where the third extension portion 31 is connected to the third connecting portion 32 to the surface of the second connecting portion 24 away from the second extension portion 25, and the inclination angle α of the second extension portion 25 and the third extension portion 31 relative to the first direction Z satisfies: α>arccos(H3 / W1), so that the fourth extension portion 33 can extend outward along the second direction X to connect with the external circuit under the inclined setting of the third extension portion 31 and avoid the fourth extension portion 33 exceeding the thickness of the battery cell.

[0067] Please refer to Figure 4. In some embodiments, the battery cell 100 also includes a packaging bag 50, and the electrode assembly 10, the tab 20, the third extension portion 31 and the third connecting portion 32 are all contained in the packaging bag 50. The end of the fourth extension portion 33 away from the third connecting portion 32 extends from the packaging bag 50 for electrical connection to an external circuit.

[0068] In some embodiments, the battery cell 100 further includes a colloid 60 , which is disposed between the fourth extension portion 33 and the packaging bag 50 to improve the connection strength and insulation stability between the tab lead 30 and the packaging bag 50 .

[0069] 5 and 6 , in some embodiments, the electrode assembly 10 includes a first electrode sheet 11, a separator 12, and a second electrode sheet 13 stacked in sequence along a first direction Z. The first electrode sheet 11 includes a first current collector 111, a first active material layer 112, and a conductive member 113. The first current collector 111 includes a first section 111a and a second section 111b sequentially arranged in a second direction X. The first active material layer 112 is connected to the first section 111a. As viewed along the first direction Z, one end of the conductive member 113 is connected to the second section 111b, and the other end of the conductive member 113 protrudes from the first current collector 111 in the second direction X and is connected to the tab unit 20a.

[0070] The first current collector 111 includes a support layer 1111, and a first conductive layer 1112 and a second conductive layer 1113 disposed on both sides of the support layer 1111 in the first direction Z. The support layer 1111 is made of a polymer insulating material and has high structural strength, low density and mass, which can reduce the thickness and weight of the first current collector 111. Optionally, the polymer insulating material includes one or more of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI), polyetherketone (PEK), and polyphenylene sulfide (PPS).

[0071] First conductive layer 1112 and second conductive layer 1113 are made of a metal material. Compared to conventional metal current collectors, first conductive layer 1112 and second conductive layer 1113, disposed on both sides of support layer 1111, are thinner. This helps reduce the generation of metal burrs when first current collector 111 is mechanically damaged by external impact, thereby reducing the risk of short circuits. Optionally, the metal material includes one or more of aluminum, copper, nickel, silver, gold, and iron.

[0072] The first active material layer 112 is connected to the first conductive layer 1112 and / or the second conductive layer 1113 located in the first section 111a. The first active material layer 112 is used to generate current and collect the current on the first current collector 111. The conductive member 113 is connected to the first conductive layer 1112 and / or the second conductive layer 1113 located in the second section 111b and is used to connect to the tab unit 20a.

[0073] Referring to Figure 7 , the battery cell 100 further includes an insulating member 70. One end of the insulating member 70 is bonded to a surface of the first active material layer 112 facing away from the first current collector 111, and the other end of the insulating member 70 is bonded to a surface of the conductive member 113 facing away from the first current collector 111. The insulating member 70 is used to improve insulation isolation of the corresponding coverage area from other structural components (e.g., the second electrode sheet 13) in the first direction Z, thereby reducing the risk of short circuits and improving the reliability of the battery cell 100.

[0074] It is understandable that the structure of the second pole piece 13 may be the same as that of the first pole piece 11 .

[0075] 8 , an embodiment of the present application further provides an electric device 200, comprising the battery cell 100 of any of the above embodiments. The electric device 200 may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, or the like.

[0076] In summary, in the battery cell 100 and electrical device 200, the first extension portion 23 and the second extension portion 25 are sequentially arranged along the second direction X on one side of the electrode assembly 10. The first connection portion 22 and the second connection portion 24 are bent, respectively. One end of the first weld mark 41 is located at the root portion 21, and the other end of the first weld mark 41 extends through the first connection portion 22 to the first extension portion 23. The second weld mark 42 is located on the second extension portion 25. This arrangement allows the tab segment located between the first weld mark 41 and the second weld mark 42 to extend along the bending direction of the second connection portion 24. This arrangement reduces the height of the tab segment in the first direction Z while ensuring the reserved spacing between the first weld mark 41 and the second weld mark 42. Furthermore, this arrangement facilitates a space of shared height in the first direction Z between the bent portion of the first weld mark 41 (i.e., the portion of the first weld mark located at the first connection portion 22) and the portion of the tab lead 30 located outside the second weld mark 42. This is beneficial to improving the space utilization of the tab 20 and the tab lead 30 in the first direction Z, and improving the energy density of the battery cell 100 .

[0077] Hereinafter, the present application will be specifically described based on Examples and Table 1, but the present application is not limited to these Examples.

[0078] Among them, the extension length L1 of the tab 20 in the longitudinal direction of the battery cell 100 (see Figure 2) is used as one parameter for comparison. The longer the extension length L1, the larger the space occupied by the tab 20. The tensile strength of the tab 20 is used as another parameter for comparison. It should be noted that the tensile strength of the weld mark portion of the tab 20 (the first weld mark 41 and the second weld mark 42) is weaker than that of other parts of the tab 20. During the stretching process of the tab 20, the weld mark portion of the tab 20 is likely to break and separate first. Therefore, the tensile strength of the tab 20 can reflect the welding reliability of the weld mark portion. The higher the tensile strength, the higher the reliability of the weld mark, and the lower the tensile strength, the lower the reliability of the weld mark.

[0079] The tensile strength of the tab 20 of each embodiment was measured using the following method. The electrode assembly 10 was fixed and the tab 20 was stretched using a tensile testing machine at a constant rate of 60 mm / min. The maximum tensile stress at the break of the first weld mark 41 or the second weld mark 42 was recorded. The ratio of the maximum tensile stress to the cross-sectional area at the break was the tensile strength of the tab 20.

[0080] It should be noted that the battery cells in each embodiment have most of the same parameters. For example, when the insulating member 70 is not provided, H1 = 2.5 mm; when the insulating member 70 is provided, H1 = 3.2 mm; H2 = 0.6 mm; and H3 = 1.2 mm. The parameters of the embodiments in the following tables, except for those mentioned, are the same.

[0081] Table 1

[0082] It can be seen from Examples 8-9 that when S1 is less than 0.5 mm, the tensile strength of the tab 20 is weak, which means that the welding reliability of the first weld mark 41 and the second weld mark 42 is affected.

[0083] It can be seen from Examples 8-11 that when S1 is greater than 2 mm, the extension length of the tab segment between the first weld mark 41 and the second weld mark 42 will be longer, resulting in space waste. When S1 is greater than 2 mm, the first weld mark 41 and the second weld mark 42 overlap in the second direction, which not only results in space waste but also causes weld mark interference, thereby reducing welding reliability.

[0084] It can be seen from Examples 1-7 that by limiting 0.5mm≤S1≤2mm, the risk of interference between the first weld mark 41 and the second weld mark 42 during the welding process is reduced, the reliability of welding is improved, and it is convenient to further improve the space utilization of the tab 20 on one side of the electrode assembly 10, which is beneficial to improve the energy density of the battery cell 100.

[0085] In addition, those skilled in the art may also make other changes within the spirit of this application. Of course, these changes made according to the spirit of this application should be included in the scope disclosed in this application.

Claims

1. A battery cell, characterized in that, The battery cell includes: An electrode assembly; A tab, including a plurality of tab units. One ends of the plurality of tab units are arranged along a first direction and are respectively connected to one side of the electrode assembly in a second direction. The other ends of the plurality of tab units converge and form a root portion, a first connection portion, a first extension portion, a second connection portion, and a second extension portion that are connected in sequence. The root portion, the first extension portion, and the second extension portion are arranged in sequence along the second direction on one side of the electrode assembly. The first connection portion and the second connection portion are respectively bent. The plurality of tab units are connected to each other and are provided with a first welding mark. One end of the first welding mark is located at the root portion, and the other end of the first welding mark extends through the first connection portion to the first extension portion. The first direction is the thickness direction of the electrode assembly, and the second direction is perpendicular to the first direction; and A tab lead. Part of the tab lead overlaps with the second extension portion in the second direction. A second welding mark is provided in the overlapping area between the tab lead and the second extension portion.

2. The battery cell according to claim 1, characterized in that, Along the extension direction of the tab, the distance S1 between the first welding mark and the second welding mark satisfies 0.5 mm ≤ S1 ≤ 2 mm; Along the second direction, the projection of the part of the first welding mark located at the first extension portion does not overlap with the second welding mark.

3. The battery cell according to claim 1, wherein, Along the second direction, the projections of the tab and the tab lead are both within the projection range of the electrode assembly.

4. The battery cell according to claim 1, characterized in that, The tab lead includes a third extension portion, a third connection portion, and a fourth extension portion that are connected in sequence. The third extension portion is arranged along the second direction on the side of the second extension portion facing the electrode assembly. At least part of the third extension portion overlaps with the second extension portion in the second direction. The second welding mark is provided in the overlapping area between the third extension portion and the second extension portion. The third connection portion is bent. The fourth extension portion extends along the second direction away from the electrode assembly.

5. The cell according to claim 4, characterized in that, The first extension portion, the second extension portion, and the third extension portion respectively extend substantially along the first direction.

6. The battery cell according to claim 4, wherein, Along the first direction, the thickness H1 of the electrode assembly satisfies: H1 ≤ 3.8 mm.

7. The battery cell according to claim 6, characterized in that, Along the first direction, the height H2 from the end point where the third connection portion is connected to the third extension portion to the surface of the fourth extension portion facing away from the third extension portion satisfies: 0.5 mm ≤ H2 ≤ 0.7 mm.

8. The battery cell according to claim 6, wherein, Along the first direction, the height H3 from the end point where the third extension portion is connected to the third connection portion to the surface of the second connection portion facing away from the second extension portion satisfies: 1 mm ≤ H3 ≤ 1.5 mm.

9. The battery cell according to claim 8, wherein, The first extension portion extends along the first direction. The second extension portion and the third extension portion both extend in the same direction inclined relative to the first direction. Along the extension direction of the tab, the extension length W1 from the end point where the third extension portion is connected to the third connection portion to the surface of the second connection portion facing away from the second extension portion, and the inclination angle α of the second extension portion and the third extension portion relative to the first direction satisfy: α > arccos(H3 / W1).

10. The battery cell according to claim 1, wherein, The electrode assembly includes a first electrode tab, a separator, and a second electrode tab that are sequentially stacked along the first direction. The first electrode tab includes a first current collector, a first active material layer, and a conductive member. The first current collector includes a first section and a second section that are sequentially arranged in the second direction. The first active material layer is connected to the first section. When observed along the first direction, one end of the conductive member is connected to the second section, and the other end of the conductive member protrudes from the first current collector in the second direction and is connected to the tab unit.

11. The battery cell according to claim 10, characterized in that, The first current collector includes a support layer, a first conductive layer, and a second conductive layer that are arranged on both sides of the support layer in the first direction. The first active material layer is connected to the first conductive layer and / or the second conductive layer located in the first section, and the conductive member is connected to the first conductive layer and / or the second conductive layer located in the second section.

12. The battery cell according to claim 10, wherein, The battery cell further includes an insulating member. One end of the insulating member is bonded to the surface of the first active material layer facing away from the first current collector, and the other end of the insulating member is bonded to the surface of the conductive member facing away from the first current collector.

13. An electrical device, characterized in that, A battery cell including the battery cell according to any one of claims 1 to 12.

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