Battery cell, battery device, electric device, and welded joint

Abstract

The application provides a battery monomer, a battery device, a power consumption device and a welding head. The battery monomer comprises a shell, an insulating support with a first through hole, an electrode assembly comprising an electrode body and a tab, and the insulating support is located on one side of the electrode body from which the tab is led out. The tab has a first welding mark area, a second welding mark area and a stress release area. The first welding mark area is located on the side of the second welding mark area close to the electrode body. The stress release area is located between the first welding mark area and the second welding mark area. At least part of the tab pieces of the first welding mark area are welded and connected. At least part of the tab pieces of the second welding mark area are welded and connected. Adjacent two layers of the tab pieces of the stress release area can move relatively. A current collecting piece is arranged on the side of the insulating support away from the electrode body. The tab is arranged through the first through hole. The stress release area is arranged in a bent mode. The second welding mark area is electrically connected with the current collecting piece. The battery monomer provided by the application is beneficial to improving the reliability of the battery monomer.

Description

Technical Field

[0001] This application relates to battery technology, and more particularly to a battery cell, battery device, power supply device, and welding head. Background Technology

[0002] Battery devices are being used more and more widely in daily life and industry. For example, new energy vehicles equipped with battery devices are now widely used.

[0003] Battery cells are a crucial component of battery devices. In the development of battery cell technology, besides improving their performance, reliability is also a key consideration. Therefore, improving the reliability of battery cells is a problem that those skilled in the art are continuously working to solve. Utility Model Content

[0004] This application provides a battery cell, a battery device, an electrical device, and a welding head, which can improve the reliability of the battery cell.

[0005] In a first aspect, the battery cell provided in this application includes a casing, an insulating support, a current collector, and at least two electrode assemblies. The casing has a receiving cavity, and the insulating support is received within the receiving cavity. The insulating support has a first through hole. The electrode assembly is received within the receiving cavity. The electrode assembly includes an electrode body and tabs. The tabs extend from the end of the electrode body, and the insulating support is located on one side of the tab extending from the electrode body. The tabs include multiple layers of tab sheets stacked together. Each tab has a first solder area, a second solder area, and a stress relief area. The first solder area is located on the side of the second solder area closer to the electrode body, and the stress relief area is located between the first and second solder areas. At least a portion of the tab sheets in the first solder area are welded together, and at least a portion of the tab sheets in the second solder area are welded together. Adjacent layers of tab sheets in the stress relief area are movable relative to each other. The current collector is located on the side of the insulating support away from the electrode body. The tabs pass through the first through hole. The stress relief area is bent. The second solder area is located on the side of the insulating support away from the electrode body and is electrically connected to the current collector, so that at least two electrode assemblies are electrically connected.

[0006] The battery cell provided in this application embodiment has a first soldering area, a second soldering area, and a stress relief area on the tab. The first soldering area can provide a certain pre-shaping effect on the side of the tab near the electrode body, reducing the risk of cracking on that side. During the process of passing the tab through the insulating support, at least part of the stress relief area bends. The multi-layer tabs in the stress relief area can release the bending stress of the tab during bending by generating relative displacement, reducing the risk of cracking during bending. The second soldering area can gather and fix at least part of the tabs, reducing the risk of cracking due to friction between the tabs and the insulating support. Therefore, the battery cell provided in this application embodiment is beneficial to reducing the risk of tab cracking and improving the reliability of the battery cell.

[0007] In some embodiments, the second solder area is located at the end of the tab away from the electrode body.

[0008] In the above embodiments, during the process of passing the tab through the first through hole, since at least a portion of the tab pieces are gathered together from the end, it is beneficial to reduce the risk of the tab pieces rubbing against the insulating support, and further beneficial to reduce the risk of the tab cracking.

[0009] In some embodiments, the insulating support has a groove on the side away from the electrode body, and the current collector is accommodated in the groove. The surface of the current collector on the side away from the electrode body is flush with the surface of the insulating support on the side away from the electrode body.

[0010] In the above embodiments, the risk of interference or scratches between the current collector and other structures is reduced. Since the current collector does not have a protruding insulating support, the risk of damage to the electrode due to mutual compression between the edge of the current collector and the tab is reduced during the electrical connection of the second solder area and the current collector. This facilitates the electrical connection between the second solder area and the current collector, and the tab does not need to be too long, thus reducing its size. This helps to reduce the current path and consequently reduce the energy loss of the battery cell. Furthermore, it helps to reduce the size of the battery cell along the thickness direction of the insulating support, improving the internal space utilization of the battery cell and thus increasing its energy density.

[0011] In some embodiments, the second solder area is welded to the side of the current collector opposite to the electrode body to form an overcurrent solder mark, and the orthogonal projection of the overcurrent solder mark is located inside the second solder area along the thickness direction of the insulating support.

[0012] In the above embodiments, by forming an overcurrent solder mark by welding a second solder area to the side of the current collector opposite to the electrode body, compared with the case of separately setting a conductive structure to connect the tab and the current collector, it is beneficial to reduce the overall size of the battery cell along the thickness direction, thereby improving the internal space utilization of the battery cell and increasing the energy density of the battery cell. Furthermore, the overcurrent solder mark has a high overcurrent capacity, which is beneficial to improving the overcurrent capacity at the connection between the current collector and the tab.

[0013] In some embodiments, the outer edge of the overflow solder mark is spaced apart from the outer edge of the second solder mark area along a direction perpendicular to the thickness direction.

[0014] In the above embodiments, the electrode tab is welded to the current collector only through the second soldering area, which is beneficial to improving the reliability of the welding connection between the current collector and the electrode tab, and also to improving the current carrying capacity at the connection between the current collector and the electrode tab.

[0015] In some embodiments, along a direction perpendicular to the thickness direction, the minimum distance d1 between the outer edge of the overcurrent solder mark and the outer edge of the second solder mark area satisfies: 1mm≤d1≤3mm.

[0016] In the above embodiment, by setting d1 to satisfy: 1mm≤d1≤3mm, it is beneficial to improve the smoothness of the welding connection between the second solder area and the current collector, and also to reduce the size of the electrode tab, so as to reduce the length of the current path of the electrode tab.

[0017] In some embodiments, the orthographic projection of the second solder area is offset from that of the first through hole along the thickness direction of the insulating support, and the edge of the second solder area near the stress relief area is spaced apart from the hole wall of the first through hole.

[0018] In the above embodiments, it is not necessary to bend the second solder area. Instead, the stress relief area can be bent to release the bending stress during the tab bending process, reduce the risk of tab cracking, and reduce the risk of the second solder area pressing against the end of the hole wall of the first through hole, thereby reducing the risk of the second solder area cracking.

[0019] In some embodiments, the minimum distance d2 between the edge of the second solder area near the stress relief area and the wall of the first through hole satisfies: 1mm≤d2≤3mm.

[0020] In the above embodiments, by setting d2 to satisfy: 1mm≤d2≤3mm, it is beneficial to reduce the risk of tab cracking and also to reduce the current path of the tab, thereby reducing the energy loss of the battery cell during the cycle operation.

[0021] In some embodiments, the insulating support has a first surface facing away from the electrode body, and the first solder area facing away from the electrode body is disposed not beyond the first surface.

[0022] In the above embodiment, after the tab passes through the first through hole, the first solder area can be straight as a whole, without needing to bend the first solder area. Bending is only required through the stress relief area, which helps to reduce the risk of tab cracking.

[0023] In some embodiments, along the thickness direction of the insulating support, the distance h1 between the edge of the first solder area near the stress relief area and the first surface satisfies: 0≤h1≤2mm.

[0024] In the above embodiment, by setting h1 to satisfy: 0≤h1≤2mm, the risk of tab cracking is reduced while the current path of the tab is reduced, which in turn helps to reduce the energy loss of the battery cell during cycle operation.

[0025] In some embodiments, the tab is spaced apart from the wall of the first through hole.

[0026] In the above embodiments, by setting the electrode tab and the hole wall of the first through hole to be spaced apart, it is beneficial to reduce the risk of the electrode tab being scratched or impacted by the hole wall of the first through hole, and further beneficial to reduce the risk of the electrode tab cracking.

[0027] In some embodiments, the battery cell includes at least two electrode assemblies, each electrode assembly including at least two tabs, and the at least two tabs of the same electrode assembly including a positive tab and a negative tab. The positive tab of one of the at least two electrode assemblies and the negative tab of the other are electrically connected to the same current collector, so that the at least two electrode assemblies are connected in series.

[0028] In the above embodiments, by setting the positive electrode tab of one of at least two electrode assemblies and the negative electrode tab of the other to be electrically connected to the same current collector, the series connection of at least two electrode assemblies is realized, which facilitates the total positive and total negative electrodes of the battery cell to be led out to the outside of the casing, so as to realize the electrical connection between different battery cells.

[0029] In some embodiments, the current collector includes copper and aluminum components that are electrically connected to each other, with the positive tab electrically connected to the aluminum component and the negative tab electrically connected to the copper component.

[0030] In the above embodiments, since the positive electrode tab is mainly made of aluminum and the negative electrode tab is mainly made of copper, the positive electrode tab is electrically connected to the aluminum component, and the negative electrode tab is electrically connected to the copper component. This helps to reduce the impedance at the electrical connection points between the positive and negative electrodes and the current collector, thereby improving the current-carrying capacity at the connection points. Furthermore, when the electrodes are welded to the current collector, this improves the reliability of the welded connections between the positive and negative electrodes and the current collector.

[0031] In some embodiments, at least two electrode assemblies are arranged along a first direction, and the positive and negative tabs of the same electrode assembly are spaced apart along a second direction. The first direction, the second direction, and the thickness direction of the insulating support intersect each other but are not coplanar. The positive tab of one of the at least two electrode assemblies and the negative tab of the other are arranged alternately along the first direction.

[0032] In the above embodiments, it is beneficial to reduce the paths through which the positive and negative tabs are electrically connected to the current collector, thereby reducing the energy loss of the battery cell during use.

[0033] In some embodiments, the battery cell includes at least three electrode assemblies, comprising a first electrode assembly, a second electrode assembly, and a third electrode assembly arranged sequentially along a first direction. The battery cell also includes at least two current collectors, comprising a first current collector and a second current collector that are insulated from each other. The positive tab of the second electrode assembly and the negative tab of the first electrode assembly are electrically connected to the first current collector, and the negative tab of the second electrode assembly and the positive tab of the third electrode assembly are electrically connected to the second current collector.

[0034] In the above embodiments, a battery cell includes at least three electrode assemblies, which helps to improve the internal space utilization of the battery cell and thus increase the energy density of the battery cell. Multiple electrode assemblies are connected in series through multiple current collectors, which helps to simplify the electrical connection between different electrode assemblies and facilitates the lead-out of the total positive and total negative electrodes of the battery cell to the outside of the casing, so as to facilitate the electrical connection between different battery cells.

[0035] In some embodiments, the battery cell includes at least two electrode assemblies and at least two current collectors. Each electrode assembly includes at least two tabs, with the at least two tabs of the same electrode assembly including a positive tab and a negative tab. The at least two current collectors include a positive current collector and a negative current collector that are insulated from each other. The positive tabs of the at least two electrode assemblies are electrically connected to the positive current collector, and the negative tabs of the at least two electrode assemblies are electrically connected to the negative current collector.

[0036] In the above embodiments, at least two electrode assemblies can be connected in parallel using one positive current collector and one negative current collector. The positive and negative electrodes of the battery cell can be led out to the outside of the casing through these two current collectors. This reduces the number of current collectors, simplifies the internal structure of the battery cell, simplifies the electrical connection between different electrode assemblies, and facilitates leading the positive and negative electrodes of the battery cell to the outside of the casing, thus enabling electrical connections between different battery cells.

[0037] Secondly, embodiments of this application provide a battery device, including the battery cell provided in any of the above embodiments.

[0038] The battery device provided in this application has the same technical effect as the battery cell provided in any embodiment of this application, and will not be described again here.

[0039] Thirdly, embodiments of this application provide an electrical device, including the battery device provided in the above embodiments, the battery device being used to provide electrical energy.

[0040] The electrical device provided in this application embodiment has the same technical effect as the battery device provided in this application embodiment, and will not be described again here.

[0041] Fourthly, the welding head provided in this application embodiment is used for welding tabs to form the battery cell provided in any of the above embodiments. The welding head includes a welding head body, a first welding tooth unit, and a second welding tooth unit. The first welding tooth unit and the second welding tooth unit are located on one side of the welding head body along a third direction, and the first welding tooth unit and the second welding tooth unit are spaced apart along a fourth direction, with the third direction and the fourth direction intersecting. The first welding tooth unit includes a plurality of spaced first welding teeth, and the second welding tooth unit includes a plurality of spaced second welding teeth. Along the third direction, the second welding teeth protrude from the first welding teeth. The first welding tooth unit is used to weld the tab to form a first solder mark area, and the second welding tooth unit is used to weld the tab to form a second solder mark area.

[0042] The welding head provided in this application can weld the tabs of the electrode assembly in any embodiment of the battery cell provided in this application by means of ultrasonic welding. In a single welding, a first solder area, a second solder area and a stress relief area with relatively precise dimensions can be formed respectively. This facilitates precise control of the accuracy and consistency of the dimensions of the first solder area, the second solder area and the stress relief area, and helps to improve the welding efficiency of the tabs.

[0043] In some embodiments, the second weld tooth is convex relative to the first weld tooth along a third direction.

[0044] In the above embodiments, after welding, the number of welding connection layers of the tabs in the second solder area can be more than the number of welding connection layers of the tabs in the first solder area, so as to realize the pre-shaping function of the first solder area for the tabs and make the first solder area have a certain anti-bending performance. The more layers of tabs in the second solder area are welded together, which is beneficial to improve the current carrying capacity of the second solder area.

[0045] In some embodiments, along a third direction, the protrusion distance h2 of the second weld tooth relative to the first weld tooth satisfies: 0.4mm≤h2≤0.8mm.

[0046] In the above embodiment, by setting h2 to satisfy 0.4mm≤h2, the number of welding layers of the tab in the second solder area is greater than that of the tab in the first solder area, thereby improving the current carrying capacity of the second solder area and giving the first solder area a certain degree of bending resistance. Setting h2≤0.8mm helps to reduce the risk of the second welding tooth burning through the second solder area of ​​the tab.

[0047] In some embodiments, the surface of the welding head body facing the first welding tooth unit has a first connecting area and a first guiding area. The first guiding area is located on the side of the first connecting area away from the second welding tooth unit. The first welding tooth unit is disposed in the first connecting area. The side of the first guiding area away from the first connecting area has a first chamfer.

[0048] In the above embodiment, by setting a first chamfer on the side of the first guide area away from the first connection area, when the part of the electrode tab located on the side of the first solder area away from the stress relief area comes into contact with the first guide area, it will first come into contact with the first chamfer, which helps to reduce the risk that the part of the electrode tab located on the side of the first solder area away from the stress relief area will be cut by the welding head body.

[0049] In some embodiments, the surface of the welding head body facing the second welding tooth unit has a second connecting area and a second guiding area. The second guiding area is located on the side of the second connecting area away from the first welding tooth unit. The second welding tooth unit is disposed in the second connecting area. The side of the second guiding area away from the second connecting area has a second chamfer.

[0050] In the above embodiment, by setting a second chamfer on the side of the second guide area away from the second connection area, when the part of the electrode located on the side of the second solder area away from the stress relief area comes into contact with the second guide area, it will first come into contact with the second chamfer, which helps to reduce the risk that the part of the electrode located on the side of the second solder area away from the stress relief area will be cut by the welding head body.

[0051] In some embodiments, the welding head body includes a main body, a first boss and a second boss. The first boss and the second boss are connected to the same side of the welding head body along a third direction. The surface of the first boss away from the welding head body has a first connecting area and a first guiding area. The first guiding area is located on both sides of the first connecting area along a fourth direction. The side of the first guiding area on both sides of the first connecting area along the fourth direction away from the first connecting area has a first chamfer.

[0052] In the above embodiment, during the welding process of the electrode tab, the first chamfer on both sides of the first connection area along the fourth direction can provide a certain guiding effect on the part of the electrode tab on the side of the first solder area away from the stress relief area and the electrode tab in the stress relief area, so as to reduce the risk of cracking of the electrode tab part in the stress relief area and the electrode tab part on the side of the first solder area away from the stress relief area.

[0053] In some embodiments, the surface of the second boss on the side away from the welding head body has a second connecting area and a second guiding area. The second guiding areas are located on both sides of the second connecting area along the fourth direction, and the side of the second guiding areas on both sides of the second connecting area away from the second connecting area has a second chamfer.

[0054] In the above embodiment, during the welding process of the electrode tab, the second chamfer on both sides of the second connection area along the fourth direction can provide a certain guiding effect for the electrode tab part on the side of the second solder area away from the stress relief area and the electrode tab in the stress relief area, respectively, so as to reduce the risk of cracking of the electrode tab part in the stress relief area and the electrode tab part in the second solder area.

[0055] In some embodiments, the first chamfer is planar, and the angle α between the first chamfer and the plane perpendicular to the third direction satisfies: 2°≤α≤15°.

[0056] In the above embodiments, it is convenient to process and shape the first chamfer. And through long-term practice, it has been found that when the electrode tab is welded, if 2°≤α≤15° is set, then α is closer to the actual bending angle of the electrode tab on the side of the first solder area that contacts the first chamfer, which is beneficial to further reduce the risk of the electrode tab cracking during the welding process.

[0057] In some embodiments, the second chamfer is planar, and the angle β between the second chamfer and the plane perpendicular to the third direction satisfies: 2°≤β≤15°. Optionally, β can be 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, or 15°, etc.

[0058] In the above embodiments, it is convenient to process and form the second chamfer. And through long-term practice, it has been found that when welding the electrode tab, setting 2°≤β≤15°, where β is closer to the actual bending angle of the electrode tab that contacts the side of the second solder area and the second chamfer, is beneficial to further reduce the risk of the electrode tab cracking during the welding process.

[0059] In some embodiments, the dimension d3 of the first chamfer along the fourth direction satisfies: 0.5mm ≤ d3 ≤ 2mm.

[0060] In the above embodiments, long-term practice has shown that during the welding process of the electrode tab, when the dimension d3 of the first chamfer along the fourth direction satisfies: 0.5mm≤d3≤2mm, the shape of the first chamfer and the part of the electrode tab that is attached to it are closer, and the electrode tab can fit better, which further helps to reduce the risk of electrode tab cracking.

[0061] In some embodiments, the dimension d4 of the second chamfer along the fourth direction satisfies: 0.5mm ≤ d4 ≤ 2mm.

[0062] In the above embodiments, long-term practice has shown that during the welding process of the electrode tab, when the dimension d4 of the second chamfer along the fourth direction satisfies: 0.5mm≤d4≤2mm, the shape of the second chamfer and the part of the electrode tab that is attached to it are closer, and the electrode tab can fit better, which further helps to reduce the risk of electrode tab cracking. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the vehicle structure provided in an embodiment of this application;

[0064] Figure 2 This is an exploded structural diagram of the battery device provided in the embodiments of this application, with some parts omitted.

[0065] Figure 3 This is a schematic diagram of the structure of a battery cell assembly in a battery device provided in an embodiment of this application;

[0066] Figure 4 This is a schematic diagram of the exploded structure of a single battery cell provided in an embodiment of this application;

[0067] Figure 5 A cross-sectional view of a partial structure of a battery cell provided for implementation of this application;

[0068] Figure 6 for Figure 5 A magnified view of a section at point A in the middle;

[0069] Figure 7 A cross-sectional view of a partial structure of another battery cell provided in an embodiment of this application;

[0070] Figure 8 A cross-sectional view of a partial structure of another battery cell provided in an embodiment of this application;

[0071] Figure 9 This is a top view of a portion of the structure of a battery cell provided in an embodiment of this application;

[0072] Figure 10 A front view of the welding head provided in an embodiment of this application;

[0073] Figure 11 for Figure 10 Bottom view of the first and second welding tooth units;

[0074] Figure 12 for Figure 10 A magnified view of a section at point B in the middle;

[0075] Figure 13 for Figure 10 A magnified view of a section at point C.

[0076] The accompanying drawings are not necessarily drawn to scale.

[0077] Explanation of reference numerals in the attached figures:

[0078] 1. Vehicle; 1a. Motor; 1b. Controller;

[0079] 10. Battery assembly; 11. Housing; 111. First sub-housing; 112. Second sub-housing;

[0080] 20. Battery cell modules;

[0081] 30. Battery cell; 30a. Overcurrent solder mark; 31. Casing; 31a. Receiving cavity; 311. Housing; 312. End cap; 32. Electrode assembly; 321. Electrode body; 322. Tab; 3221. Positive tab; 3222. Negative tab; 322a. First solder mark area; 322b. Second solder mark area; 322c. Stress relief area; 33. Insulating support; 33a. First through hole; 33b. Groove; 33c. First surface; 34. Current collector; 341. Copper component; 342. Aluminum component;

[0082] 40. Welding head; 41. Welding head body; 411. Body section; 412. First boss; 412a. First connecting area; 412b. First guide area; 412b1. First chamfer; 413. Second boss; 413a. Second connecting area; 413b. Second guide area; 413b1. Second chamfer; 42. First welding tooth unit; 421. First welding tooth; 43. Second welding tooth unit; 431. Second welding tooth;

[0083] X, first direction; Y, second direction; Z, thickness direction; M, third direction; N, fourth direction. Detailed Implementation

[0084] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0085] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having”, and any variations thereof, in the specification and the foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0086] In the description of the embodiments of this application, the technical terms "first," "second," "third," etc., are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0087] In this document, the term "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 throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0088] In the description of the embodiments 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, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects are in an "or" relationship.

[0089] In the description of the embodiments of this application, the technical terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "top", "bottom", "inner", "outer", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed, operated or used in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0090] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0091] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical term "contact" should be interpreted broadly, and can be direct contact, contact through an intermediate medium layer, contact between two contacting parties with substantially no interaction force, or contact between two contacting parties with interaction force.

[0092] In the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering. Specifically, if the angle between two directions is 85°-90°, the two directions can be considered perpendicular; if the angle between two directions is 0°-5°, the two directions can be considered parallel.

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

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

[0095] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. There are no particular limitations in the embodiments of this application.

[0096] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0097] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0098] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0099] In some implementations, the electrode assembly is a stacked structure.

[0100] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0101] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0102] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0103] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0104] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0105] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0106] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0107] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0108] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0109] In some embodiments, a pressure relief mechanism is provided on the casing of the battery cell. The pressure relief mechanism is used to release the internal gas of the battery cell.

[0110] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of a battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is destroyed, thereby forming an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0111] As an example, the pressure relief mechanism can be integrally formed with the housing.

[0112] As an example, the pressure relief mechanism can also be separately installed and connected to the outer casing.

[0113] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0114] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.

[0115] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0116] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0117] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0118] As an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into an independent module. As an example, the battery module can be formed by bundling multiple battery cells together with cable ties.

[0119] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0120] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0121] As an example, the battery cell assembly can also be housed in the housing by directly fixing multiple battery cells to the housing.

[0122] As an example, the enclosure may include a first sub-enclosure and a second sub-enclosure. The first and second sub-enclosures are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or shutting down; it can be sealed or not sealed. The first enclosure may be a top cover or a bottom plate.

[0123] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and the bottom plate are respectively connected to the frame, so that the interior of the enclosure forms a closed space to accommodate the individual battery cells.

[0124] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0125] A single battery cell typically includes an electrode assembly, which consists of an electrode body and tabs. The tabs extend from one end of the electrode body and are welded to a current collector to facilitate current transmission. The current collector is supported on an insulating support, and the tabs must pass through the insulating support before being electrically connected to the current collector.

[0126] In related technologies, the tabs of electrode assemblies typically need to be welded to current collectors to draw electrical energy from the electrode assembly through the current collectors. The electrode body and current collector of the electrode assembly are located on opposite sides of an insulating support. The tabs need to pass through the insulating support and undergo a certain bend before they can be electrically connected to the current collector. Studies have shown that stress concentration is prone to occur in the bending area of ​​the tabs, which can lead to tab cracking. This seriously affects the reliability of the battery cell.

[0127] In view of this, the present application provides a battery cell including a casing, an insulating support, at least two electrode assemblies, and a current collector. The casing has a receiving cavity, the insulating support is received within the receiving cavity, the insulating support has a first through hole, the electrode assembly is received within the receiving cavity, the electrode assembly includes an electrode body and tabs, the tabs are led out from the end of the electrode body, the insulating support is located on one side of the lead-out tab of the electrode body, the tabs include multiple layers of tab sheets stacked together, the tabs have a first soldering area, a second soldering area, and a stress relief area, the first soldering area is located on the side of the second soldering area close to the electrode body, the stress relief area is located between the first soldering area and the second soldering area, at least some of the tab sheets in the first soldering area are welded together, at least some of the tab sheets in the second soldering area are welded together, and adjacent two layers of tab sheets in the stress relief area can move relative to each other. The current collector is located on the side of the insulating support away from the electrode body, the electrode tab is inserted through the first through hole, at least part of the stress relief area is bent, and the second solder area is located on the side of the insulating support away from the electrode body and is electrically connected to the current collector so that at least two electrode assemblies are electrically connected.

[0128] The battery cell provided in this application embodiment has a first soldering area, a second soldering area, and a stress relief area on the tab. The first soldering area can provide a certain pre-shaping effect on the side of the tab near the electrode body, reducing the risk of cracking on that side. During the process of passing the tab through the insulating support, at least part of the stress relief area bends. The multi-layer tab sheets in the stress relief area can release the bending stress of the tab during bending by generating relative displacement, reducing the risk of cracking during bending. The second soldering area can reduce the risk of cracking due to friction between the tab sheets and the insulating support. Therefore, the battery cell provided in this application embodiment is beneficial to reducing the risk of tab cracking and improving the reliability of the battery cell.

[0129] The technical solutions described in the embodiments of this application are applicable to battery cells, battery devices including battery cells, electrical devices using battery cells, and welding heads for welding the tabs of battery cells.

[0130] The battery device disclosed in this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using the battery device disclosed in this application.

[0131] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric bicycles, electric motorcycles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0132] For ease of explanation, the following embodiments will be described using a vehicle 1 as an example of an electrical device according to an embodiment of this application.

[0133] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1 provided in an embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 10 is installed inside vehicle 1, and the battery device 10 can be located at the bottom, front, or rear of vehicle 1. The battery device 10 can be used to power vehicle 1; for example, the battery device 10 can serve as the operating power source for vehicle 1's electrical system, such as meeting the power requirements for starting, navigation, and operation of vehicle 1.

[0134] The vehicle 1 may also include a controller 1b and a motor 1a. The controller 1b is used to control the battery device 10 to supply power to the motor 1a, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0135] In some embodiments of this application, the battery device 10 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.

[0136] Please refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the structure of the battery device 10 provided in the embodiments of this application. Figure 3 This is a schematic diagram of the structure of the battery cell assembly 20 in the battery device 10 provided in this application embodiment. The battery device 10 includes a housing 11 and battery cells 30, with the battery cells 30 housed within the housing 11. The housing 11 provides a space for accommodating the battery cells 30, and the housing 11 can adopt various structures. In some embodiments, the housing 11 may include a first sub-housing 111 and a second sub-housing 112, which overlap each other, and together define a space for accommodating the battery cells 30. The second sub-box 112 can be a hollow structure with one end open, and the first sub-box 111 can be a plate-like structure. The first sub-box 111 covers the opening side of the second sub-box 112 so that the first sub-box 111 and the second sub-box 112 together define the accommodating space. Alternatively, the first sub-box 111 and the second sub-box 112 can both be hollow structures with one side open, and the opening side of the first sub-box 111 covers the opening side of the second sub-box 112.

[0137] In the battery device 10, there can be multiple battery cells 30, which can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 30 are connected in both series and parallel configurations. Multiple battery cells 30 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 30 is housed within the housing 11. Alternatively, the battery device 10 can also consist of multiple battery cells 30 first connected in series, parallel, or in a mixed manner to form a battery cell assembly 20, and then the multiple battery cell assemblies 20 are connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 11. The battery device 10 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 30.

[0138] Among them, the battery cell 30 can be a secondary battery or a primary battery; the battery cell 30 can also be a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited to these.

[0139] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the exploded structure of a battery cell 30 provided in an embodiment of this application. Figure 4 As shown, the battery cell 30 includes a housing 31 and an electrode assembly 32. The housing 31 includes a casing 311 and an end cap 312. The casing 311 has an opening, and the end cap 312 closes the opening to isolate the internal environment of the battery cell 30 from the external environment.

[0140] Firstly, such as Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the battery cell 30 provided in this embodiment includes a housing 31, an insulating support 33, a current collector 34, and at least two electrode assemblies 32. The housing 31 has a receiving cavity 31a, and the insulating support 33 is received within the receiving cavity 31a. The insulating support 33 has a first through hole 33a. The electrode assembly 32 is received within the receiving cavity 31a. The electrode assembly 32 includes an electrode body 321 and a tab 322. The tab 322 extends from the end of the electrode body 321. The insulating support 33 is located on the side of the electrode body 321 from which the tab 322 extends. 22 includes multiple layers of tabs stacked together. Each tab 322 has a first solder area 322a, a second solder area 322b, and a stress relief area 322c. The first solder area 322a is located on the side of the second solder area 322b closest to the electrode body 321. The stress relief area 322c is located between the first solder area 322a and the second solder area 322b. At least a portion of the tabs in the first solder area 322a and at least a portion of the tabs in the second solder area 322b are welded together. Adjacent layers of tabs in the stress relief area 322c are movable relative to each other. A current collector 34 is disposed on the side of the insulating support 33 facing away from the electrode body 321. The tabs 322 pass through a first through hole 33a. At least a portion of the stress relief area 322c is bent. The second solder area 322b is located on the side of the insulating support 33 facing away from the electrode body 321 and is electrically connected to the current collector 34, thereby electrically connecting at least two electrode assemblies 32.

[0141] The outer casing 31 provides protection for the electrode assembly 32 and other related components within it. The outer casing 31 can be cylindrical, polygonal, or other shapes. The outer casing 31 may include a housing 311 and an end cap 312. The end cap 312 may be plate-shaped, and the housing 311 may be a hollow polyhedral structure. The end cap 312 covers the housing 311, and the end cap 312 and housing 311 together define a receiving cavity 31a. The housing 311 may include multiple interconnected walls, with adjacent walls intersecting. Optionally, the multiple walls of the housing 311 may be integrally formed by processes such as pultrusion, or the housing 311 may be composed of multiple plate-shaped walls connected together by processes such as welding.

[0142] The battery cell 30 may also include an electrolyte. During the charging and discharging process of the battery cell 30, the electrolyte serves as a transport channel for metal ions, which can be lithium ions, sodium ions, or magnesium ions, etc. During the cyclic charging and discharging of the battery cell 30, metal ions repeatedly intercalate and deintercalate between the positive and negative electrodes, and in this process, the metal ions need to pass through the electrolyte. The electrolyte can be a solid electrolyte or a liquid electrolyte, selected according to actual needs.

[0143] Both the insulating support 33 and the current collector 34 are housed in the receiving cavity 31a. The insulating support 33 can provide a certain support for the current collector 34. A single battery cell 30 can include multiple current collectors 34. Different current collectors 34 are supported by the insulating support 33 respectively, and the insulating support 33 can provide a certain insulation for different current collectors 34.

[0144] The electrode assembly 32 includes an electrode body 321 and tabs 322. The tabs 322 can be areas on the metal current collector of the electrode sheet that are not coated with an active material layer, and they play a certain role in overcurrent during the cyclic charging and discharging of the battery cell 30. An electrode assembly 32 may include at least two tabs 322, one of which can be a positive tab 3221 and the other can be a negative tab 3222. The positive tab 3221 and the negative tab 3222 can be led out from the same end of the electrode body 321, or the positive tab 3221 and the negative tab 3222 can be led out from opposite ends of the electrode body 321.

[0145] In embodiments where the positive tab 3221 and the negative tab 3222 extend from the same end of the electrode body 321, a single battery cell 30 may include an insulating support 33 located on the side of the end of the electrode body 321 where the tab 322 extends. In embodiments where the positive tab 3221 and the negative tab 3222 extend from opposite ends of the electrode body 321, the single battery cell 30 may include two insulating supports 33, which may be located on opposite sides of the electrode body 321.

[0146] The tab 322 passes through the first through hole 33a of the insulating support 33 and is electrically connected to the current collector 34 on the side of the insulating support 33 opposite to the electrode body 321. Two electrode assemblies 32 can be electrically connected to the same current collector 34 to achieve parallel, series, or mixed connections of different electrode assemblies 32. For example, to achieve parallel connection of two electrode assemblies 32, the two same-polarity tabs 322 of the two electrode assemblies 32 can be electrically connected through two different current collectors 34. To achieve series connection of two electrode assemblies 32, the two opposite-polarity tabs 322 of the two electrode assemblies 32 can be electrically connected to the same current collector 34. In this way, by setting the connection method of the tabs 322 of different electrode components 32 to the current collector 34 respectively, multiple electrode components 32 of the same battery cell 30 can be connected in series, in parallel or in combination. Then, the total positive and total negative terminals of multiple electrode components 32 are led out to the outside of the housing 31 through conductive components such as electrode terminals, so as to facilitate the electrical connection between the battery cell 30 and the external circuit.

[0147] Therefore, the current collector 34 can provide a certain current flow to the electrode assembly 32, so as to realize the electrical connection between different electrode assemblies 32, and facilitate the lead-out of the total positive and total negative terminals of the electrically connected electrode assembly 32 to the outside of the housing 31.

[0148] The first soldering area 322a of the tab 322 can be spaced apart from the end of the tab 322 that connects to the electrode body 321. A portion of adjacent tabs in the multilayer tabs of the first soldering area 322a can be soldered together, or any two adjacent tabs in the multilayer tabs of the first soldering area 322a can be soldered together. The second soldering area 322b can be located at the end of the tab 322 away from the electrode body 321. A portion of adjacent tabs in the multilayer tabs of the second soldering area 322b can be soldered together, or any two adjacent tabs in the multilayer tabs of the first soldering area 322a can be soldered together.

[0149] The first solder area 322a can improve the structural strength and support stiffness of the tab 322 in the corresponding area, so that the first solder area 322a can have a more stable structure during the production of the battery cell 30 and after the battery cell 30 is produced, reducing the risk of cracking on the side of the tab 322 close to the electrode body 321 under external vibration or impact. Furthermore, the first solder area 322a can provide a certain pre-shaping effect for the tab 322, reducing the risk of some tab pieces of the tab 322 bending and breaking.

[0150] During the production of the battery cell 30, the tab 322 needs to be passed from one side of the insulating support 33 to the other. The second solder area 322b can provide a certain shaping effect on the end of the tab 322 away from the electrode body 321, so as to provide a certain gathering and fixing effect on at least part of the tab in the second solder area 322b, reducing the risk of the tab 322 scraping against the insulating support 33 during the process of passing through the first through hole 33a of the insulating support 33. Furthermore, since the second solder area 322b is electrically connected to the current collector 34, the second solder area 322b can improve the current carrying capacity of the tab 322 in the corresponding area, thereby improving the current carrying capacity at the electrical connection between the second solder area 322b and the current collector 34.

[0151] During the assembly of the battery cell 30, due to manufacturing errors, the tab 322 may not be perfectly aligned with the first through hole 33a. Alternatively, after the tab 322 passes through the first through hole 33a, it needs to be bent to achieve electrical connection between the second solder area 322b and the current collector 34. In other words, at least part of the tab 322 may be bent during its passage through the first through hole 33a. Since the adjacent tab layers in the stress relief area 322c can move relative to each other, the relative movement of the adjacent tab layers in the stress relief area 322c can reduce the bending stress on the tab 322 and lower the risk of cracking during the bending process.

[0152] The second solder area 322b and the current collector 34 can be electrically connected by welding, or the second solder area 322b can simply abut against the current collector 34 without welding. The electrode body 321 is located on one side of the insulating support 33 along the thickness direction Z. Optionally, the second solder area 322b can be welded or abutted against the side of the current collector 34 along the thickness direction Z away from the electrode body 321, or the second solder area 322b can be welded or abutted against the side of the current collector 34 perpendicular to the thickness direction Z.

[0153] The current collector 34 may be fully or partially embedded in the insulating support 33 on the side opposite to the electrode body 321, or the current collector 34 may not be embedded in the interior of the insulating support 33, but may protrude from the surface of the insulating support 33.

[0154] The battery cell 30 provided in this embodiment has a first soldering area 322a, a second soldering area 322b, and a stress relief area 322c on its tab 322. The first soldering area 322a can provide a certain pre-shaping effect on the side of the tab 322 near the electrode body 321, reducing the risk of cracking on that side. During the process of passing the tab 322 through the insulating support 33, at least part of the stress relief area 322c bends. The multilayer tabs in the stress relief area 322c can release the bending stress of the tab 322 during bending by generating relative displacement, reducing the risk of cracking during bending. The second soldering area 322b can reduce the risk of cracking due to friction between the tab and the insulating support 33. Therefore, the battery cell 30 provided in this embodiment is beneficial to reducing the risk of tab 322 cracking and improving the reliability of the battery cell 30.

[0155] In some embodiments, such as Figure 7 and Figure 8 As shown, the second solder area 322b is located at the end of the tab 322 opposite to the electrode body 321.

[0156] Specifically, during the production of the battery cell 30, the tab 322 can be welded first, and then the tab 322 can be cut. The irregular welding area of ​​the tab 322 away from the electrode body 321 is cut off, so that the second solder area 322b is located at the end of the tab 322 away from the electrode.

[0157] In this way, during the process of passing the tab 322 through the first through hole 33a, the end of the tab 322 away from the electrode body 321, namely the second solder area 322b, enters the first through hole 33a first. Since at least some of the tabs in the second solder area 322b are welded together, at least some of the tabs are gathered and fixed from the end, which helps to reduce the risk of the tabs rubbing against the insulating support 33, and further helps to reduce the risk of the tab 322 cracking.

[0158] In some embodiments, such as Figure 5 , Figure 6 and Figure 7 As shown, the insulating support 33 has a groove 33b on the side away from the electrode body 321, and the current collector 34 is accommodated in the groove 33b. The surface of the current collector 34 on the side away from the electrode body 321 is flush with the surface of the insulating support 33 on the side away from the electrode body 321.

[0159] Thus, the current collector 34 is embedded inside the insulating support 33. The current collector 34 and the insulating support 33 are flush with each other on the sides away from the electrode body 321. Here, "flush" does not mean that they are absolutely flush; they can be absolutely flush, or one of them can be set to protrude from the other within the allowable error range. For example, the distance between the surfaces of the current collector 34 and the insulating support 33 on the sides away from the electrode body 321 can be in the range of 0~1mm.

[0160] By setting a groove 33b and accommodating a current collector 34 within it, with the surfaces of the current collector 34 and the insulating support 33 respectively facing away from the electrode body 321 being flush, the risk of interference or scratches between the current collector 34 and other structures is reduced. Furthermore, since the current collector 34 does not protrude from the insulating support 33, the risk of damage to the electrode 322 due to mutual compression between the edge of the current collector 34 and the tab 322 is reduced during the electrical connection of the second soldering area 322b and the current collector 34. This facilitates the electrical connection between the second soldering area 322b and the current collector 34, and the tab 322 does not need to be too long, thus reducing its size. This helps to reduce the current path and consequently reduce the energy loss of the battery cell 30. It also helps to reduce the dimension of the battery cell 30 along the thickness direction Z of the insulating support 33, improving the internal space utilization of the battery cell 30 and thus increasing its energy density.

[0161] In some embodiments, such as Figure 5 and Figure 6 As shown, the second solder area 322b is welded to the side of the current collector 34 away from the electrode body 321 to form an overcurrent solder mark 30a. Along the thickness direction Z of the insulating support 33, the orthogonal projection of the overcurrent solder mark 30a is located inside the second solder area 322b.

[0162] In other words, during the production of the battery cell 30, the tabs 322 can be welded first to form a first solder area 322a and a second solder area 322b. Then, at least a portion of the second solder area 322b is welded to the current collector 34 to form an overcurrent solder mark 30a.

[0163] The term "overcurrent solder mark 30a" refers to a welding mark with the expected current carrying capacity, which can be determined according to design requirements. Superficially, the overcurrent solder mark 30a can be a welding mark formed after the tab 322 and the current collector 34 are welded together. Its shape can be regular or irregular, and it represents the necessary path for current to flow between the tab 322 and the current collector 34.

[0164] The second solder mark area 322b is welded to the side of the current collector 34 opposite to the electrode body 321. The area of ​​the welded connection can be set as needed without considering the space occupied by the connection in the thickness direction Z, thus saving the space inside the battery cell 30 along the thickness direction Z. This is beneficial to improving the space utilization rate inside the battery cell 30, thereby increasing the energy density of the battery cell 30. The welded connection has strong connection reliability, and the overcurrent solder mark 30a formed after welding has high overcurrent capacity, which is beneficial to improving the overcurrent capacity at the electrical connection between the tab 322 and the current collector 34.

[0165] Optionally, the edge of the orthographic projection of the overcurrent solder mark 30a along the thickness direction Z can be flush with the edge of the orthographic projection of the second solder mark area 322b along the thickness direction Z, or the edge of the orthographic projection of the overcurrent solder mark 30a along the thickness direction Z and the edge of the orthographic projection of the second solder mark area 322b along the thickness direction Z can be spaced apart. In this way, the tab 322 is welded to the current collector 34 only through the second solder mark area 322b, which helps to improve the reliability of the welded connection and the overcurrent capacity at the connection between the tab 322 and the current collector 34.

[0166] Understandably, depending on the different solder areas of the second solder area 322b and the current collector 34, in the final battery cell 30 product, the second solder area 322b can completely overlap with the overcurrent solder 30a, or the second solder area 322b can be arranged around the periphery of the overcurrent solder 30a. Alternatively, a portion of the outer periphery of the overcurrent solder 30a can overlap with the second solder area 322b, while another portion is surrounded by the second solder area 322b.

[0167] Therefore, by forming a current-carrying solder mark 30a by welding the second solder mark area 322b to the side of the current collector 34 opposite to the electrode body 321, compared to the case where a separate conductive structure is used to connect the tab 322 and the current collector 34, it is beneficial to reduce the overall size of the battery cell 30 along the thickness direction Z, thereby improving the internal space utilization of the battery cell 30 and increasing the energy density of the battery cell 30. Furthermore, the current-carrying solder mark 30a has a higher current-carrying capacity, which is beneficial to improving the current-carrying capacity at the connection between the current collector 34 and the tab 322.

[0168] In some embodiments, such as Figure 5 and Figure 6 As shown, along the direction perpendicular to the thickness direction Z, the outer edge of the overflow solder mark 30a and the outer edge of the second solder mark area 322b are spaced apart.

[0169] In this way, after the battery cell 30 is produced, the second soldering area 322b is set around the overcurrent soldering area 30a, and the tab 322 is only welded to the current collector 34 through the second soldering area 322b. This is beneficial to improving the reliability of the welding connection between the current collector 34 and the tab 322, and also to improving the overcurrent capacity at the connection between the current collector 34 and the tab 322.

[0170] In some embodiments, such as Figure 5 and Figure 6 As shown, along the direction perpendicular to the thickness direction Z, the minimum distance d1 between the outer edge of the overcurrent solder mark 30a and the outer edge of the second solder mark area 322b satisfies: 1mm≤d1≤3mm.

[0171] Optionally, d1 can be 1mm, 1.5mm, 2mm, 2.5mm, or 3mm, etc. The distance between the outer edge of the overcurrent solder mark 30a and the outer edge of the second solder mark area 322b is not exactly the same at different positions, and d1 is the minimum value of the distance between the outer edge of the overcurrent solder mark 30a and the outer edge of the second solder mark area 322b.

[0172] It is understandable that the larger the value of d1 is to a certain extent, the more conducive it is to the smooth welding connection between the second solder area 322b and the current collector 34, and the more conducive it is to improving the current carrying capacity. On the other hand, the smaller the value of d1 is to a certain extent, the more conducive it is to reduce the size of the tab 322, so as to reduce the length of the current carrying path of the tab 322. During the operation of the battery cell 30, it is more conducive to reducing energy loss.

[0173] Therefore, by setting d1 to satisfy: 1mm≤d1≤3mm, it is beneficial to improve the smoothness of the welding connection between the second solder area 322b and the current collector 34, and also beneficial to reduce the size of the tab 322, so as to reduce the length of the current path of the tab 322.

[0174] In some embodiments, such as Figure 5 and Figure 6 As shown, along the thickness direction Z of the insulating support 33, the orthographic projection of the second solder area 322b is offset from the first through hole 33a, and the edge of the second solder area 322b near the stress relief area 322c is spaced apart from the hole wall of the first through hole 33a.

[0175] In other words, no part of the orthogonal projection of the second solder area 322b along the thickness direction Z falls into the first through hole 33a, and the edge of the second solder area 322b is spaced apart from the first through hole 33a in a direction perpendicular to the thickness direction Z. In this way, the second solder area 322b is located on the side of the insulating support 33 away from the electrode body 321 and can be straight.

[0176] It is understandable that after the tab 322 is inserted into the first through hole 33a, in order to achieve welding or contact between the second solder area 322b and the current collector 34, at least a portion of the tab 322 needs to be bent. Since the edge of the second solder area 322b is spaced apart from the first through hole 33a, it is not necessary to bend the second solder area 322b. Instead, the stress relief area 322c is bent. In the final product, at least a portion of the stress relief area 322c is bent. Since the multiple tabs in the stress relief area 322c can generate relative displacement, the bending stress during the bending process of the tab 322 is released, which helps to reduce the risk of the tab 322 cracking.

[0177] Furthermore, during the process of welding or abutting the second solder area 322b to the current collector 34, the second solder area 322b needs to be positioned close to the insulating support 33. By setting the edge of the second solder area 322b near the stress relief area 322c to be spaced apart from the wall of the first through hole 33a, the risk of the second solder area 322b pressing against the end of the wall of the first through hole 33a is reduced, thereby reducing the risk of the second solder area 322b cracking.

[0178] In some embodiments, such as Figure 5 and Figure 6 As shown, the minimum distance d2 between the edge of the second solder area 322b near the stress relief area 322c and the wall of the first through hole 33a satisfies: 1mm≤d2≤3mm.

[0179] Optionally, d2 can be 1mm, 1.5mm, 2mm, 2.5mm, or 3mm, etc. The distance between the edge of the second solder area 322b near the stress relief area 322c and the wall of the first through hole 33a is not exactly the same, and d2 is the minimum distance between the edge of the second solder area 322b and the first through hole 33a.

[0180] Understandably, the larger the distance d2 between the edge of the second solder area 322b and the wall of the first through hole 33a, the more beneficial it is to reduce the pressure of the tab 322 on the insulating support 33 during the electrical connection between the second solder area 322b and the current collector 34, thus reducing the risk of the tab 322 cracking. Conversely, the smaller the distance d2 between the edge of the second solder area 322b and the wall of the first through hole 33a, the more beneficial it is to reduce the size of the tab 322, thereby reducing the current path of the tab 322 and reducing power loss.

[0181] Therefore, by setting d2 to satisfy: 1mm≤d2≤3mm, it is beneficial to reduce the risk of tab 322 cracking, and also to reduce the current path of tab 322, so as to reduce the energy loss of battery cell 30 during cycle operation.

[0182] In some embodiments, such as Figure 5 and Figure 6 As shown, the insulating support 33 has a first surface 33c on the side opposite to the electrode body 321, and the first solder area 322a is disposed on the side opposite to the electrode body 321 without extending beyond the first surface 33c.

[0183] The side of the first solder area 322a that is away from the electrode body 321 is the side of the first solder area 322a that faces the stress relief area 322c. Optionally, the side of the first solder area 322a that is away from the electrode body 321 can be flush with the first surface 33c, or it can be located inside the first through hole 33a and spaced apart from the first surface 33c.

[0184] In this way, after the tab 322 passes through the first through hole 33a, the first solder area 322a can be straight as a whole, without needing to bend the first solder area 322a. It is only bent through the stress relief area 322c, which helps to reduce the risk of the tab 322 cracking.

[0185] In some embodiments, such as Figure 5 and Figure 6 As shown, along the thickness direction Z of the insulating support 33, the distance h1 between the edge of the first solder area 322a near the stress relief area 322c and the first surface 33c satisfies: 0≤h1≤2mm.

[0186] Optionally, h1 can be 0, 0.5mm, 1mm, 1.5mm or 2mm, etc.

[0187] It is understandable that the smaller h1 is to a certain extent, the more beneficial it is to reduce the current path of the tab 322, so as to reduce the energy loss of the battery cell 30 during operation.

[0188] Therefore, by setting h1 to satisfy: 0≤h1≤2mm, the risk of tab 322 cracking is reduced, and the current path of tab 322 is reduced, which in turn helps to reduce the energy loss of battery cell 30 during cycle operation.

[0189] In some embodiments, such as Figure 5 and Figure 6 As shown, the tab 322 is spaced apart from the wall of the first through hole 33a.

[0190] Thus, during the process of the tab 322 passing through the first through hole 33a, it helps to reduce the risk of the tab 322 scratching the hole wall of the first through hole 33a and cracking. After the tab 322 passes through the first through hole 33a, when the battery cell 30 is subjected to loads such as impact or vibration during use, it helps to reduce the risk of the tab 322 expanding and cracking the hole wall of the first through hole 33a.

[0191] Therefore, by setting the tab 322 and the hole wall of the first through hole 33a to be spaced apart, it is beneficial to reduce the risk of the tab 322 being scratched or impacted by the hole wall of the first through hole 33a, and further beneficial to reduce the risk of the tab 322 cracking.

[0192] In some embodiments, such as Figure 7 As shown, the battery cell 30 includes at least two electrode assemblies 32, and each electrode assembly 32 includes at least two tabs 322. The at least two tabs 322 of the same electrode assembly 32 include a positive tab 3221 and a negative tab 3222. The positive tab 3221 of one of the at least two electrode assemblies 32 and the negative tab 3222 of the other are respectively electrically connected to the same current collector 34, so that the at least two electrode assemblies 32 are connected in series.

[0193] Optionally, the battery cell 30 may include two, three or more electrode assemblies 32, and the multiple electrode assemblies 32 may be arranged along a direction perpendicular to the thickness direction Z.

[0194] In an embodiment where the battery cell 30 includes only two electrode assemblies 32, the positive tab 3221 of one of the two electrode assemblies 32 and the negative tab 3222 of the other can be electrically connected to different areas of the same current collector 34. The other negative tab 3222 and the other positive tab 3221 of the two electrode assemblies 32 are electrically connected to two other current collectors 34, so that they can be led out to the outside of the housing 31 through the other two current collectors 34, and form the total positive and total negative electrodes of the battery cell 30.

[0195] In embodiments where the battery cell 30 includes three or more electrode assemblies 32, the multiple electrode assemblies 32 can be arranged along a first direction X perpendicular to the thickness direction Z. Among the multiple electrode assemblies 32, the positive electrode tab 3221 of an electrode assembly 32 with other electrode assemblies 32 on both sides of the first direction X is electrically connected to the negative electrode tab 3222 of another electrode assembly 32 on one side of the first direction X to the same current collector 34. The negative electrode tab 3222 is electrically connected to the positive electrode tab 3221 of another electrode assembly 32 on the other side of the first direction X to another current collector 34. The positive electrode tab 3221 of one of the two electrode assemblies 32 located on both sides and the negative electrode tab 3222 of the other are respectively electrically connected to two current collectors 34 so that they are led out to the outside of the casing 31 through the two current collectors 34, and constitute the total positive and total negative electrodes of the battery cell 30.

[0196] It is understandable that in embodiments where the positive tab 3221 and the negative tab 3222 are connected to the same current collector 34, the current collector 34 can be integrally formed and made of the same material, with different areas of the current collector 34 electrically connected to the positive tab 3221 and the negative tab 3222 respectively. Alternatively, since the positive tab 3221 and the negative tab 3222 are made of different materials, the current collector 34 can also be made of different materials that are electrically connected to each other, so that the areas electrically connected to the positive tab 3221 and the negative tab 3222 respectively have corresponding materials, which facilitates the welding connection of the positive tab 3221 and the negative tab 3222 to different parts of the current collector 34 respectively.

[0197] By setting the positive electrode tab 3221 of one of the at least two electrode assemblies 32 and the negative electrode tab 3222 of the other to be electrically connected to the same current collector 34, the series connection of at least two electrode assemblies 32 is realized, which facilitates the lead-out of the total positive and total negative electrodes of the battery cell 30 to the outside of the casing 31, so as to realize the electrical connection between different battery cells 30.

[0198] In some embodiments, such as Figure 7 As shown, the current collector 34 includes a copper component 341 and an aluminum component 342 that are electrically connected to each other. The positive electrode tab 3221 is electrically connected to the aluminum component 342, and the negative electrode tab 3222 is electrically connected to the copper component 341.

[0199] Since the positive tab 3221 is mainly made of aluminum and the negative tab 3222 is mainly made of copper, the positive tab 3221 is electrically connected to the aluminum component 342 and the negative tab 3222 is electrically connected to the copper component 341. This helps to reduce the impedance at the electrical connection points of the positive tab 3221 and the negative tab 3222 with the current collector 34, and improves the current carrying capacity at the connection point of the tab 322 and the current collector 34.

[0200] In the embodiment where the positive electrode tab 3221 is welded to the aluminum component 342 and the negative electrode tab 3222 is welded to the copper component 341, it is beneficial to improve the reliability of the welding connection between the positive electrode tab 3221 and the negative electrode tab 3222 and the current collector 34 respectively.

[0201] In some embodiments, such as Figure 7 , Figure 8 and Figure 9 As shown, at least two electrode assemblies 32 are arranged along the first direction X, and the positive electrode tab 3221 and negative electrode tab 3222 of the same electrode assembly 32 are arranged at intervals along the second direction Y. The first direction X, the second direction Y and the thickness direction Z of the insulating support member 33 intersect each other but are not coplanar. The positive electrode tab 3221 of one of the at least two electrode assemblies 32 and the negative electrode tab 3222 of the other are arranged alternately along the first direction X.

[0202] The positive electrode tab 3221 and the negative electrode tab 3222 of the same electrode assembly 32 can be led out from the same end of the electrode body 321 along the thickness direction Z, or the positive electrode tab 3222 of the same electrode assembly 32 can be led out from opposite ends of the electrode body 321 along the thickness direction Z.

[0203] At least two electrode assemblies 32 have their positive tabs 3221 and negative tabs arranged alternately along the first direction X. The first direction X, the second direction Y, and the thickness direction Z can be perpendicular to each other. In this way, the positive tabs 3221 and negative tabs 3222 of multiple electrode assemblies 32 are arranged in two columns along the first direction X, and multiple electrode assemblies 32 can be connected in series through multiple current-passing devices.

[0204] In two adjacent electrode assemblies 32, the positive tab 3221 of one and the negative tab 3222 of the other are electrically connected to the same current collector 34. By arranging the positive tab 3221 and the negative tab 3222 of the electrode assembly 32 alternately along the first direction X, it is beneficial to reduce the path of the positive tab 3221 and the negative tab 3222 being electrically connected to the current collector 34, thereby reducing the energy loss of the battery cell 30 during use.

[0205] In some embodiments, such as Figure 8 and Figure 9 As shown, the battery cell 30 includes at least three electrode assemblies 32, each comprising a first electrode assembly, a second electrode assembly, and a third electrode assembly arranged sequentially along a first direction X. The battery cell 30 also includes at least two current collectors 34, each comprising a first current collector and a second current collector that are insulated from each other. The positive tab 3221 of the second electrode assembly and the negative tab 3222 of the first electrode assembly are electrically connected to the first current collector, respectively. The negative tab 3222 of the second electrode assembly and the positive tab 3221 of the third electrode assembly are electrically connected to the second current collector, respectively.

[0206] The battery cell 30 may include three, four, or more electrode assemblies 32, all of which are arranged along a first direction X. The positive tab 3221 of at least one electrode assembly 32 located between two electrode assemblies 32 on opposite sides of the first direction X is electrically connected to the negative tab 3222 of the electrode assembly 32 on one side of the first direction X via a current collector 34. The negative tab 3222 is electrically connected to the positive tab 3221 of the electrode assembly 32 on the other side of the first direction X via another current collector 34. This process is repeated, and the multiple electrode assemblies 32 arranged along the first direction X are connected in series with each other via multiple current collectors 34.

[0207] It should be noted that the terms "first electrode assembly," "second electrode assembly," and "third electrode assembly" here merely specify the arrangement order of multiple electrode assemblies 32, and do not refer to any specific electrode assembly 32. In different combinations of three electrode assemblies 32, the specific electrode assembly 32 referred to by "first electrode assembly," "second electrode assembly," and "third electrode assembly" may differ. The same electrode assembly 32 may occupy different positions in different combinations of three electrode assemblies 32, and may respectively serve as the first electrode assembly, the second electrode assembly, and the third electrode assembly.

[0208] A single battery cell 30 includes at least three electrode assemblies 32, which helps to improve the internal space utilization of the battery cell 30 and thus increase the energy density of the battery cell 30. The multiple electrode assemblies 32 are connected in series through multiple current collectors 34, which helps to simplify the electrical connection between different electrode assemblies 32 and facilitates the lead-out of the total positive and total negative terminals of the battery cell 30 to the outside of the casing 31, so as to facilitate the electrical connection between different battery cells 30.

[0209] In some embodiments, the battery cell 30 includes at least two electrode assemblies 32 and at least two current collectors 34. Each electrode assembly 32 includes at least two tabs 322, with each tab 322 comprising a positive tab 3221 and a negative tab 3222. Each of the at least two current collectors 34 includes a positive current collector and a negative current collector 34 that are insulated from each other. The positive tabs 3221 of the at least two electrode assemblies 32 are electrically connected to the positive current collector, and the negative tabs 3222 of the at least two electrode assemblies 32 are electrically connected to the negative current collector.

[0210] The positive current collector may be made of aluminum, while the negative current collector 34 may be made of copper. The positive tabs 3221 of at least two electrode assemblies 32 are electrically connected to the positive current collector, and the negative tabs 3222 of at least two electrode assemblies 32 are electrically connected to the negative current collector 34, so as to realize the parallel connection of at least two electrode assemblies 32.

[0211] For example, multiple electrode assemblies 32 are arranged along a first direction X. Positive tabs 3221 and negative tabs 3222 of the multiple electrode assemblies 32 are arranged along the first direction X. A positive current collector can extend along the first direction X, and a negative current collector 34 can extend along the first direction X. The positive current collector and the negative current collector 34 are spaced apart from each other and insulated. The positive tabs 3221 of the multiple electrode assemblies 32 are each electrically connected to the same positive current collector, and the negative tabs 3222 of the multiple electrode assemblies 32 are each electrically connected to the same negative current collector 34.

[0212] Thus, at least two electrode assemblies 32 can be connected in parallel through a positive current collector and a negative current collector 34, and the total positive and negative electrodes of the battery cell 30 can be led out to the outside of the casing 31 through the aforementioned positive and negative current collectors 34. This is beneficial for reducing the number of current collectors 34, simplifying the internal structure of the battery cell 30, simplifying the electrical connection method between different electrode assemblies 32, and facilitating the leading out of the total positive and negative electrodes of the battery cell 30 to the outside of the casing 31, thereby facilitating the electrical connection between different battery cells 30.

[0213] Secondly, the battery device provided in the embodiments of this application includes the battery cell 30 provided in any of the above embodiments.

[0214] The battery device provided in this application has the same technical effect as the battery cell 30 provided in any embodiment of this application, and will not be described again here.

[0215] Thirdly, the electrical device provided in the embodiments of this application includes the battery device provided in the above embodiments, and the battery device is used to provide electrical energy.

[0216] The electrical device provided in this application embodiment has the same technical effect as the battery device provided in this application embodiment, and will not be described again here.

[0217] Fourthly, such as Figure 5 , Figure 10 and Figure 11 As shown, the welding head 40 provided in this embodiment is used to weld and form the tab 322 of the battery cell 30 provided in any of the above embodiments. The welding head 40 includes a welding head body 41, a first welding tooth unit 42, and a second welding tooth unit 43. The first welding tooth unit 42 and the second welding tooth unit 43 are located on one side of the welding head body 41 along a third direction M. The first welding tooth unit 42 and the second welding tooth unit 43 are spaced apart along a fourth direction N, and the third direction M and the fourth direction N intersect. The first welding tooth unit 42 includes a plurality of spaced first welding teeth 421, and the second welding tooth unit 43 includes a plurality of spaced second welding teeth 431. Along the third direction M, the second welding teeth 431 protrude from the first welding teeth 421. The first welding tooth unit 42 is used to weld the tab 322 to form a first solder mark area 322a, and the second welding tooth unit 43 is used to weld the tab 322 to form a second solder mark area 322b.

[0218] The welding head body 41 can provide support for the first welding tooth unit 42 and the second welding tooth unit 43, thereby enabling them to move. Optionally, the first welding tooth unit 42 can be integrally formed with the welding head body 41, or the first welding tooth unit 42 and the welding head body 41 can be separately formed and then connected together by welding, bonding, or other connection methods. Similarly, the second welding tooth unit 43 can be integrally formed with the welding head body 41, or the second welding tooth unit 43 and the welding head body 41 can be separately formed and then connected together by welding, bonding, or other connection methods.

[0219] The plurality of first welding teeth 421 of the first welding tooth unit 42 can be arranged in an array along any two directions perpendicular to the third direction M, and the plurality of second welding teeth 431 of the second welding tooth unit 43 can be arranged in an array along any two directions perpendicular to the third direction M.

[0220] The welding head 40 provided in this application embodiment can be used to weld the tab 322 of the battery cell 30 provided in this application embodiment by ultrasonic welding to form a first solder area 322a and a second solder area 322b respectively.

[0221] Specifically, during the production of the battery cell 30, the tab 322 is placed on a welding table, with the stacking direction of the tab pieces parallel to the third direction M, while the arrangement direction of the first solder area 322a, the stress relief area 322c, and the second solder area 322b is parallel to the fourth direction N. Using the welding head 40 provided in this embodiment, the first welding tooth unit 42 and the second welding tooth unit 43 are respectively positioned corresponding to the first solder area 322a and the second solder area 322b. During the welding process, the welding head 40 generates high-frequency vibration, and the first welding tooth 421 and the second welding tooth 431 respectively squeeze and rub the tab pieces of the first solder area 322a and the second solder area 322b, so that high temperature is generated between the interfaces of the tab pieces, reaching or approaching the recrystallization temperature of the pieces, resulting in plastic deformation. As the welding process continues, plastic flow occurs between adjacent tab pieces and they diffuse into each other, forming a solid metallurgical bond. In this way, after the welding head 40 is welded to the tab 322, it can form a first solder mark area 322a and a second solder mark area 322b respectively.

[0222] The area of ​​the tab 322 located between the first welding tooth unit 42 and the second welding tooth unit 43 does not have a welding connection between the tabs because it is not squeezed by the welding head 40. Therefore, relative movement can occur, and a stress relief zone 322c is formed.

[0223] The dimensions of the first welding tooth unit 42 can be set according to the required dimensions of the first solder area 322a, the dimensions of the second welding tooth unit 43 can be set according to the required dimensions of the second solder area 322b, and the spacing between the first welding tooth unit 42 and the second welding tooth unit 43 along the fourth direction N can be set according to the required dimensions of the stress relief area 322c. In this way, the dimensions of the first solder area 322a, the second solder area 322b, and the stress relief area 322c can be controlled more precisely, which is beneficial to improving the welding efficiency of the tab 322.

[0224] The surfaces of the first welding tooth 421 and the second welding tooth 431 on the side away from the welding head body 41 can be flush or not flush. The first welding tooth 421 can be set to protrude from the second welding tooth 431 along the third direction M, or the second welding tooth 431 can be set to protrude from the first welding tooth 421 along the third direction M.

[0225] The welding head 40 provided in this application embodiment can weld the tabs 322 of the electrode assembly 32 in any embodiment of the battery cell 30 by ultrasonic welding. In a single welding operation, a first solder area 322a, a second solder area 322b, and a stress relief area 322c with relatively precise dimensions can be formed respectively. This facilitates precise control of the accuracy and consistency of the dimensions of the first solder area 322a, the second solder area 322b, and the stress relief area 322c, and helps to improve the welding efficiency of the tabs 322.

[0226] In some embodiments, such as Figure 10 As shown, along the third direction M, the second welding tooth 431 is protruding relative to the first welding tooth 421.

[0227] The second welding tooth 431 protrudes relative to the first welding tooth 421. During the welding process, the clamping force of the second welding tooth 431 on the second welding area 322b of the tab 322 is greater than the clamping force of the first welding tooth 421 on the first welding area 322a of the tab 322. As a result, after welding, the number of welding connection layers of the tab pieces in the second welding area 322b can be more than the number of welding connection layers of the tab pieces in the first welding area 322a. This achieves the pre-shaping function of the first welding area 322a on the tab 322 and makes some tab pieces in the first welding area 322a unwelded, thereby giving the first welding area 322a a certain degree of bending resistance. The more layers of tab pieces welded together in the second welding area 322b are beneficial to improving the current carrying capacity of the second welding area 322b.

[0228] In some embodiments, such as Figure 10 As shown, along the third direction M, the protrusion distance h2 of the second welding tooth 431 relative to the first welding tooth 421 satisfies: 0.4mm≤h2≤0.8mm.

[0229] Optionally, h2 can be 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm, etc.

[0230] Understandably, a larger protrusion distance h2 of the second welding tooth 431 relative to the first welding tooth 421 is more beneficial for increasing the difference in clamping force borne by the second solder area 322b and the first solder area 322a of the electrode tab 322. This increases the number of welding layers of the electrode tab in the second solder area 322b after welding, thereby improving the current carrying capacity of the second solder area 322b and reducing the number of welding layers of the electrode tab in the first solder area 322a, giving the first solder area 322a a certain degree of bending resistance. Conversely, a smaller h2 is more beneficial for reducing the risk of burn-through in the second solder area 322b.

[0231] Therefore, by setting h2 to satisfy 0.4mm≤h2, the number of welding layers of the tab in the second solder area 322b is greater than that of the tab in the first solder area 322a, thereby improving the current carrying capacity of the second solder area 322b and giving the first solder area 322a a certain degree of bending resistance. Setting h2≤0.8mm helps reduce the risk that the second welding tooth 431 will weld through the second solder area 322b of the tab 322.

[0232] In some embodiments, such as Figure 10 and Figure 12 As shown, the surface of the welding head body 41 facing the first welding tooth unit 42 has a first connecting area 412a and a first guiding area 412b. The first guiding area 412b is located on the side of the first connecting area 412a away from the second welding tooth unit 43. The first welding tooth unit 42 is disposed in the first connecting area 412a. The side of the first guiding area 412b away from the first connecting area 412a has a first chamfer 412b1.

[0233] The surface of the welding head body 41 facing the first welding tooth unit 42 is the surface of the welding head body 41 facing the tab 322 during the welding process. During the welding process, the first welding tooth 421 abuts against the first weld mark area 322a of the tab 322. The tab 322 is close to the surface of the welding head body 41 facing the first welding tooth unit 42. The part of the tab 322 located on the side of the first weld mark area 322a away from the stress relief area 322c has a greater risk of abutting against the first guide area 412b.

[0234] Optionally, the first chamfer 412b1 can be an arc-shaped chamfer, or the first chamfer 412b1 can be a planar inclined shape. The first chamfer 412b1 can reduce the risk of the surface of the welding head body 41 facing the tab 322 causing the tab 322 to be cut, and further reduce the risk of the tab 322 cracking.

[0235] The first guide area 412b can be provided only on the side of the first connecting area 412a away from the second welding tooth unit 43, or the first guide area 412b can be provided on both sides of the first connecting area 412a along the fourth direction N, or, in order to reduce the processing complexity, the first guide area 412b can be provided around the first connecting area 412a. Correspondingly, the first chamfer 412b1 can be provided only on the side of the first connecting area 412a away from the second welding tooth unit 43, or the first chamfer 412b1 can be provided on both sides of the first connecting area 412a along the fourth direction N, or the first chamfer 412b1 can be provided on the outer periphery of the first connecting area 412a.

[0236] By setting a first chamfer 412b1 on the side of the first guide area 412b away from the first connection area 412a, when the part of the tab 322 located on the side of the first solder area 322a away from the stress relief area 322c comes into contact with the first guide area 412b, it will first come into contact with the first chamfer 412b1. This helps to reduce the risk that the part of the tab 322 located on the side of the first solder area 322a away from the stress relief area 322c will be cut by the welding head body 41.

[0237] In some embodiments, such as Figure 10 and Figure 13 As shown, the surface of the welding head body 41 facing the second welding tooth unit 43 has a second connecting area 413a and a second guiding area 413b. The second guiding area 413b is located on the side of the second connecting area 413a away from the first welding tooth unit 42. The second welding tooth unit 43 is disposed in the second connecting area 413a. The side of the second guiding area 413b away from the second connecting area 413a has a second chamfer 413b1.

[0238] The surface of the welding head body 41 facing the second welding tooth unit 43 is the surface of the welding head body 41 facing the tab 322 during the welding process. During the welding process, the second welding tooth 431 abuts against the second weld area 322b of the tab 322. The tab 322 is close to the surface of the welding head body 41 facing the second welding tooth unit 43. The part of the tab 322 located on the side of the second weld area 322b away from the stress relief area 322c has a greater risk of abutting against the second guide area 413b.

[0239] It should be noted that the second solder area 322b can be located on the edge of the tab 322 away from the electrode body 321. However, during the soldering process, the second solder area 322b is not necessarily located on the edge of the tab 322 away from the electrode body 321. Instead, a certain amount of machining allowance can be left on the side of the second solder area 322b away from the electrode body 321 of the tab 322. This allowance can be cut off after soldering. Tearing of the machining allowance portion of the tab 322 may cause the entire tab 322 to tear. Therefore, it is also necessary to reduce the risk of tearing of this portion of the tab 322.

[0240] Optionally, the second chamfer 413b1 can be an arc-shaped chamfer, or the second chamfer 413b1 can be a planar inclined shape. The second chamfer 413b1 can reduce the risk of the surface of the welding head body 41 facing the tab 322 causing the tab 322 to be cut, and further reduce the risk of the tab 322 cracking.

[0241] The second guide area 413b can be provided only on the side of the second connecting area 413a away from the first welding tooth unit 42, or the second guide area 413b can be provided on both sides of the second connecting area 413a along the fourth direction N, or, in order to reduce the processing complexity, the second guide area 413b can be provided around the second connecting area 413a. Correspondingly, the second chamfer 413b1 can be provided only on the side of the second connecting area 413a away from the first welding tooth unit 42, or the second chamfer 413b1 can be provided on both sides of the second connecting area 413a along the fourth direction N, or the second chamfer 413b1 can be provided on the outer periphery of the second connecting area 413a.

[0242] By setting a second chamfer 413b1 on the side of the second guide area 413b away from the second connection area 413a, when the part of the tab 322 located on the side of the second solder area 322b away from the stress relief area 322c comes into contact with the second guide area 413b, it will first come into contact with the second chamfer 413b1. This helps to reduce the risk that the part of the tab 322 located on the side of the second solder area 322b away from the stress relief area 322c will be cut by the welding head body 41.

[0243] In some embodiments, such as Figure 10 and Figure 12As shown, the welding head body 41 includes a main body 411, a first boss 412 and a second boss 413. The first boss 412 and the second boss 413 are connected to the same side of the welding head body 41 along the third direction M. The surface of the first boss 412 away from the welding head body 41 has a first connecting area 412a and a first guiding area 412b. The first guiding area 412b is located on both sides of the first connecting area 412a along the fourth direction N. The side of the first guiding area 412b on both sides of the first connecting area 412a away from the first connecting area 412a has a first chamfer 412b1.

[0244] The main body 411, the first boss 412, and the second boss 413 can be integrally formed, or they can be separately formed and then connected together by welding or other means. The first welding tooth 421 and the first boss 412 can be integrally formed, or they can be separately formed and then connected together. Similarly, the second welding tooth 431 and the second boss 413 can be integrally formed, or they can be separately formed and then connected together.

[0245] The first connecting area 412a has a first guide area 412b on both sides along the fourth direction N, and each has a first chamfer 412b1. During the welding process of the tab 322, the first chamfers 412b1 on both sides of the first connecting area 412a along the fourth direction N can provide a certain guiding effect on the part of the tab 322 on the side of the first solder area 322a away from the stress relief area 322c and the tab 322 in the stress relief area 322c, so as to reduce the risk of cracking of the part of the tab 322 in the stress relief area 322c and the part of the tab 322 on the side of the first solder area 322a away from the stress relief area 322c.

[0246] In some embodiments, such as Figure 10 and Figure 13 As shown, the surface of the second boss 413 opposite to the welding head body 41 has a second connecting area 413a and a second guiding area 413b. The second guiding area 413b is located on both sides of the second connecting area 413a along the fourth direction N. The second guiding area 413b on both sides of the second connecting area 413a along the fourth direction N has a second chamfer 413b1 on the side away from the second connecting area 413a.

[0247] The second connecting area 413a has a second guide area 413b on both sides along the fourth direction N, and each has a second chamfer 413b1. During the welding process of the tab 322, the second chamfer 413b1 on both sides of the second connecting area 413a along the fourth direction N can provide a certain guiding effect for the tab 322 part of the second solder area 322b on the side away from the stress relief area 322c and the tab 322 of the stress relief area 322c, so as to reduce the risk of cracking of the tab 322 part of the stress relief area 322c and the tab 322 part of the second solder area 322b.

[0248] In some embodiments, such as Figure 12 As shown, the first chamfer 412b1 is planar, and the angle α between the first chamfer 412b1 and the plane perpendicular to the third direction M satisfies: 2°≤α≤15°.

[0249] Optionally, α can be 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, or 15°, etc.

[0250] This facilitates the processing and shaping of the first chamfer 412b1. Furthermore, long-term practice has shown that when welding the tab 322, setting 2°≤α≤15° makes α closer to the actual bending angle of the tab 322 on the side of the first solder area 322a that contacts the first chamfer 412b1, which helps to further reduce the risk of the tab 322 cracking during the welding process.

[0251] In some embodiments, such as Figure 13 As shown, the second chamfer 413b1 is planar, and the angle β between the second chamfer 413b1 and the plane perpendicular to the third direction M satisfies: 2°≤β≤15°. Optionally, β can be 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, or 15°, etc.

[0252] This facilitates the processing and forming of the second chamfer 413b1. Furthermore, long-term practice has shown that setting 2°≤β≤15° during the welding process of the tab 322, with β being closer to the actual bending angle of the tab 322 where the side of the second solder area 322b contacts the second chamfer 413b1, helps to further reduce the risk of the tab 322 cracking during the welding process.

[0253] In some embodiments, such as Figure 12 As shown, the dimension d3 of the first chamfer 412b1 along the fourth direction N satisfies: 0.5mm≤d3≤2mm.

[0254] Optionally, d3 can be 0.5mm, 1mm, 1.5mm or 2mm, etc.

[0255] Through long-term practice, it has been found that during the welding process of tab 322, when the dimension d3 of the first chamfer 412b1 along the fourth direction N satisfies the condition that 0.5mm≤d3≤2mm, the shape of the first chamfer 412b1 and the part of tab 322 that is attached to it are closer, and they can fit better with tab 322, which further helps to reduce the risk of tab 322 cracking.

[0256] In some embodiments, such as Figure 13 As shown, the dimension d4 of the second chamfer 413b1 along the fourth direction N satisfies: 0.5mm≤d4≤2mm.

[0257] Optionally, d4 can be 0.5mm, 1mm, 1.5mm or 2mm, etc.

[0258] Through long-term practice, it has been found that during the welding process of tab 322, when the dimension d4 of the second chamfer 413b1 along the fourth direction N satisfies the condition that 0.5mm≤d4≤2mm, the shape of the second chamfer 413b1 and the part of tab 322 that is attached to it are closer, and they can fit better with tab 322, which further helps to reduce the risk of tab 322 cracking.

[0259] In some embodiments, such as Figures 4 to 9As shown, the battery cell 30 provided in this embodiment includes a housing 31, an insulating support 33, at least two electrode assemblies 32, and a current collector 34. The housing 31 has a receiving cavity 31a, and the insulating support 33 is received within the receiving cavity 31a. The insulating support 33 has a first through hole 33a. The electrode assembly 32 is received within the receiving cavity 31a. The electrode assembly 32 includes an electrode body 321 and a tab 322. The tab 322 extends from the end of the electrode body 321. The insulating support 33 is located on the side of the electrode body 321 from which the tab 322 extends. 22 includes multiple layers of tabs stacked together. The tab 322 has a first solder area 322a, a second solder area 322b, and a stress relief area 322c. The first solder area 322a is located on the side of the second solder area 322b close to the electrode body 321. The stress relief area 322c is located between the first solder area 322a and the second solder area 322b. At least a portion of the tabs in the first solder area 322a are welded together. At least a portion of the tabs in the second solder area 322b are welded together. The adjacent two layers of tabs in the stress relief area 322c can move relative to each other. A current collector 34 is disposed on the side of the insulating support 33 facing away from the electrode body 321. A tab 322 passes through the first through hole 33a and is spaced apart from the hole wall of the first through hole 33a. At least a portion of the stress relief zone 322c is bent. A second solder area 322b is located on the side of the insulating support 33 facing away from the electrode body 321 and is electrically connected to the current collector 34, thereby electrically connecting at least two electrode assemblies 32. The second solder area 322b is located at the end of the tab 322 facing away from the electrode body 321. The side of the insulating support 33 facing away from the electrode body 321 has a groove 33b, in which the current collector 34 is accommodated. The surface of the current collector 34 facing away from the electrode body 321 is flush with the surface of the insulating support 33 facing away from the electrode body 321. The second solder area 322b is welded to the side of the current collector 34 opposite to the electrode body 321 to form a current-carrying solder mark 30a. Along the thickness direction Z of the insulating support 33, the orthographic projection of the current-carrying solder mark 30a is located inside the second solder area 322b. Along a direction perpendicular to the thickness direction Z, the minimum distance d1 between the outer edge of the current-carrying solder mark 30a and the outer edge of the second solder area 322b satisfies: 1mm ≤ d1 ≤ 3mm. Along the thickness direction Z of the insulating support 33, the orthographic projection of the second solder area 322b is offset from the first through hole 33a, and the minimum distance d2 between the edge of the second solder area 322b near the stress relief area 322c and the wall of the first through hole 33a satisfies: 1mm ≤ d2 ≤ 3mm. The insulating support 33 has a first surface 33c on the side opposite to the electrode body 321. The side of the first solder area 322a opposite to the electrode body 321 does not extend beyond the first surface 33c. The distance h1 between the edge of the first solder area 322a near the stress relief area 322c and the first surface 33c satisfies: 0≤h1≤2mm.The battery cell 30 includes at least two electrode assemblies 32, each electrode assembly 32 including at least two tabs 322. Each electrode assembly 32 has a positive tab 3221 and a negative tab 3222. The positive tab 3221 of one electrode assembly 32 and the negative tab 3222 of the other are electrically connected to the same current collector 34, thereby connecting the at least two electrode assemblies 32 in series. The current collector 34 includes a copper component 341 and an aluminum component 342 electrically connected to each other. The positive tab 3221 is electrically connected to the aluminum component 342, and the negative tab 3222 is electrically connected to the copper component 341. At least two electrode assemblies 32 are arranged along the first direction X. The positive electrode tab 3221 and the negative electrode tab 3222 of the same electrode assembly 32 are arranged at intervals along the second direction Y. The first direction X, the second direction Y and the thickness direction Z of the insulating support 33 intersect each other but are not coplanar. The positive electrode tab 3221 of one of the at least two electrode assemblies 32 and the negative electrode tab 3222 of the other are arranged alternately along the first direction X.

[0260] The battery cell 30 provided in this application embodiment has a first soldering area 322a, a second soldering area 322b, and a stress relief area 322c on the tab 322. The first soldering area 322a can provide a certain pre-shaping effect on the side of the tab 322 near the electrode body 321, reducing the risk of cracking on the side of the tab 322 near the electrode body 321. During the process of passing the tab 322 through the insulating support 33, at least part of the stress relief area 322c bends. The multilayer tabs in the stress relief area 322c can release the bending stress of the tab 322 during the bending process by generating relative displacement, reducing the risk of cracking of the tab 322 during bending. The second soldering area 322b can gather and fix at least part of the tabs, reducing the risk of cracking due to friction between the tabs and the insulating support 33. Therefore, the battery cell 30 provided in this application embodiment is beneficial to reducing the risk of cracking of the tab 322 and improving the reliability of the battery cell 30.

[0261] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: The outer shell has a receiving cavity; An insulating support member is accommodated within the accommodating cavity, and the insulating support member has a first through hole; At least two electrode assemblies are housed within the receiving cavity. Each electrode assembly includes an electrode body and a tab. The tab extends from the end of the electrode body, and the insulating support is located on the side of the electrode body where the tab extends. Each tab includes multiple layers of tab sheets stacked together. Each tab has a first solder area, a second solder area, and a stress relief area. The first solder area is located on the side of the second solder area closer to the electrode body, and the stress relief area is located between the first solder area and the second solder area. At least a portion of the tab sheets in the first solder area are welded together, and at least a portion of the tab sheets in the second solder area are welded together. Adjacent layers of tab sheets in the stress relief area are movable relative to each other. A current collector is disposed on the side of the insulating support away from the electrode body. The electrode tab passes through the first through hole. At least a portion of the stress relief area is bent. The second solder area is located on the side of the insulating support away from the electrode body and is electrically connected to the current collector, thereby electrically connecting at least two electrode assemblies.

2. The battery cell according to claim 1, characterized in that, The second solder mark area is located at the end of the tab that is away from the electrode body.

3. The battery cell according to claim 1, characterized in that, The insulating support has a groove on the side away from the electrode body, and the current collector is accommodated in the groove. The surface of the current collector on the side away from the electrode body is flush with the surface of the insulating support on the side away from the electrode body.

4. The battery cell according to claim 1, characterized in that, The second solder area is welded to the side of the current collector opposite to the electrode body to form an overcurrent solder mark. The orthogonal projection of the overcurrent solder mark is located inside the second solder area along the thickness direction of the insulating support.

5. The battery cell according to claim 4, characterized in that, Along a direction perpendicular to the thickness direction, the outer edge of the overflow solder mark is spaced apart from the outer edge of the second solder mark area.

6. The battery cell according to claim 5, characterized in that, Along a direction perpendicular to the thickness direction, the minimum distance d1 between the outer edge of the overcurrent solder mark and the outer edge of the second solder mark area satisfies: 1mm≤d1≤3mm.

7. The battery cell according to claim 1, characterized in that, Along the thickness direction of the insulating support, the orthographic projection of the second solder area is offset from the first through hole, and the edge of the second solder area near the stress relief area is spaced apart from the hole wall of the first through hole.

8. The battery cell according to claim 7, characterized in that, The minimum distance d2 between the edge of the second solder area near the stress relief area and the wall of the first through hole satisfies: 1mm≤d2≤3mm.

9. The battery cell according to claim 1, characterized in that, The insulating support has a first surface facing away from the electrode body, and the first solder area facing away from the electrode body is not disposed beyond the first surface.

10. The battery cell according to claim 9, characterized in that, Along the thickness direction of the insulating support, the distance h1 between the edge of the first solder area near the stress relief area and the first surface satisfies: 0≤h1≤2mm.

11. The battery cell according to claim 1, characterized in that, The electrode tab is spaced apart from the wall of the first through hole.

12. The battery cell according to any one of claims 1 to 11, characterized in that, The battery cell includes at least two electrode assemblies, and the electrode assembly includes at least two tabs. The at least two tabs of the same electrode assembly include a positive tab and a negative tab. The positive tab of at least two of the electrode assemblies and the negative tab of the other are respectively electrically connected to the same current collector, so that the at least two electrode assemblies are connected in series.

13. The battery cell according to claim 12, characterized in that, The current collector includes a copper component and an aluminum component that are electrically connected to each other. The positive electrode tab is electrically connected to the aluminum component, and the negative electrode tab is electrically connected to the copper component.

14. The battery cell according to claim 12, characterized in that, At least two of the electrode assemblies are arranged along a first direction, and the positive and negative tabs of the same electrode assembly are spaced apart along a second direction. The first direction, the second direction, and the thickness direction of the insulating support intersect each other but are not coplanar. The positive tab of one of the at least two electrode assemblies and the negative tab of the other are arranged alternately along the first direction.

15. The battery cell according to claim 14, characterized in that, The battery cell includes at least three electrode assemblies, the at least three electrode assemblies including a first electrode assembly, a second electrode assembly and a third electrode assembly arranged sequentially along the first direction, and the battery cell includes at least two current collectors, the at least two current collectors including a first current collector and a second current collector that are mutually insulated from each other. The positive tab of the second electrode assembly and the negative tab of the first electrode assembly are electrically connected to the first current collector, and the negative tab of the second electrode assembly and the positive tab of the third electrode assembly are electrically connected to the second current collector.

16. The battery cell according to any one of claims 1 to 11, characterized in that, The battery cell includes at least two electrode assemblies and at least two current collectors. The electrode assembly includes at least two tabs, and the at least two tabs of the same electrode assembly include a positive tab and a negative tab. The at least two current collectors include a positive current collector and a negative current collector that are insulated from each other. The positive tabs of at least two of the electrode assemblies are electrically connected to the positive current collector, and the negative tabs of at least two of the electrode assemblies are electrically connected to the negative current collector.

17. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 16.

18. An electrical appliance, characterized in that, Includes the battery device as described in claim 17, the battery device being used to provide electrical energy.

19. A welding head, characterized in that, For welding the tabs to form the battery cell as described in any one of claims 1 to 16, the welding head comprises: Welding head body; A first welding tooth unit and a second welding tooth unit are disposed on one side of the welding head body along a third direction. The first welding tooth unit and the second welding tooth unit are spaced apart along a fourth direction, and the third direction intersects with the fourth direction. The first welding tooth unit includes a plurality of spaced first welding teeth, and the second welding tooth unit includes a plurality of spaced second welding teeth. Along the third direction, the second welding teeth protrude from the first welding teeth. The first welding tooth unit is used to weld the electrode tab to form the first weld mark area, and the second welding tooth unit is used to weld the electrode tab to form the second weld mark area.

20. The welding head according to claim 19, characterized in that, Along the third direction, the second welding tooth is protruding relative to the first welding tooth.

21. The welding head according to claim 20, characterized in that, Along the third direction, the protrusion distance h2 of the second welding tooth relative to the first welding tooth satisfies: 0.4mm≤h2≤0.8mm.

22. The welded joint according to any one of claims 19 to 21, characterized in that, The surface of the welding head body facing the first welding tooth unit has a first connecting area and a first guiding area. At least a portion of the first guiding area is located on the side of the first connecting area away from the second welding tooth unit. The first welding tooth unit is disposed in the first connecting area. The side of the first guiding area away from the first connecting area has a first chamfer; and / or, The surface of the welding head body facing the second welding tooth unit has a second connecting area and a second guiding area. At least a portion of the second guiding area is located on the side of the second connecting area away from the first welding tooth unit. The second welding tooth unit is disposed in the second connecting area. The side of the second guiding area away from the second connecting area has a second chamfer.

23. The welding joint according to claim 22, characterized in that, The welding head body includes a main body, a first boss, and a second boss. The first boss and the second boss are connected to the same side of the welding head body along the third direction. The surface of the first boss facing away from the welding head body has a first connecting area and a first guiding area. The first guiding areas are located on both sides of the first connecting area along the fourth direction. The side of the first guiding area on both sides of the first connecting area along the fourth direction away from the first connecting area has the first chamfer; and / or, The surface of the second boss on the side away from the welding head body has a second connecting area and a second guiding area. The second guiding area is located on both sides of the second connecting area along the fourth direction. The side of the second guiding area on both sides of the second connecting area along the fourth direction away from the second connecting area has a second chamfer.

24. The welding joint according to claim 22, characterized in that, The first chamfer is planar, and the angle α between the first chamfer and the plane perpendicular to the third direction satisfies: 2°≤α≤15°; and / or, the second chamfer is planar, and the angle β between the second chamfer and the plane perpendicular to the third direction satisfies: 2°≤β≤15°.

25. The welding joint according to claim 22, characterized in that, The dimension d3 of the first chamfer along the fourth direction satisfies: 0.5mm≤d3≤2mm; and / or, the dimension d of the second chamfer along the fourth direction satisfies: 0.5mm≤d4≤2mm.

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