Welding horn, ultrasonic welding device, battery cell, battery, and electric device

Abstract

A welding horn, an ultrasonic welding device comprising the welding horn, a battery cell processed by the ultrasonic welding device, a battery comprising the battery cell, and an electric device comprising the battery. A welding end (401) of the welding horn (400) is provided with welding teeth (5) and tooth grooves (6), the welding teeth are divided by the tooth grooves into a plurality of tooth portions (51) spaced apart, and the tooth area ratio of the welding end is greater than or equal to 40%. The arrangement of the welding teeth on the welding horn increases the area ratio of a compaction region in ultrasonic welding, so that more contour lines of laser welding imprints fall within the compaction region, mitigating the problem of thermal cracks along the contours of the laser welding imprints.

Description

Welding head, ultrasonic welding device, battery cell, battery and electrical device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202420691915.0 and application date 2024-04-03, and claims the priority of the above-mentioned Chinese patent application. The entire content of the above-mentioned Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a welding head, an ultrasonic welding device, a battery cell, a battery, and an electrical device. Background Art

[0004] In recent years, new energy vehicles have experienced rapid development. In the electric vehicle sector, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. Power batteries consist of several battery cells, but the reliability of these cells needs to be improved.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can improve the reliability of the battery cell.

[0007] In a first aspect, an embodiment of the present application provides a welding head, wherein the welding end of the welding head has welding teeth and tooth grooves, the welding teeth are divided into a plurality of tooth portions arranged at intervals by the tooth grooves, and the tooth area of ​​the welding end accounts for greater than or equal to 40%.

[0008] In the above technical solution, by setting the tooth area ratio of the welding end to no less than 40%, the area ratio of the compacted area in the ultrasonic weld mark can be increased, so that the contour line of the laser weld mark falls more into the compacted area, so as to improve the problem of thermal cracks in the contour of the laser weld mark to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear and the conductive part, and improving the reliability of the battery cell.

[0009] In some embodiments, the tooth groove includes a first straight groove and a second straight groove arranged crosswise, there are multiple first straight grooves and they are arranged in parallel, a tooth portion is defined between adjacent first straight grooves and second straight grooves, and the groove width of the first straight groove and the groove width of the second straight groove are both smaller than the spacing between adjacent first straight grooves.

[0010] In the above technical solution, the grooves are divided into weld teeth by linear grooves, making the grooves easy to machine and reducing processing costs. Furthermore, this helps reduce the area of ​​the grooves, increasing the area of ​​the teeth defined between adjacent first and second linear grooves, thereby increasing the area of ​​the teeth at the weld end. This allows the contour of the laser weld mark to fall more deeply into the compacted area, further alleviating the problem of thermal cracking in the laser weld mark contour. This, in turn, improves the conductivity yield and connection strength between the tab and the conductive portion, enhancing the reliability of the battery cell.

[0011] In some embodiments, the spacing between adjacent first straight grooves is 1.5 mm to 2.5 mm.

[0012] In the above technical solution, it is helpful to improve the grip during welding to provide greater friction and to increase the tooth area ratio of the welding end.

[0013] In some embodiments, there are multiple second linear grooves arranged in parallel, teeth are defined between adjacent first linear grooves and adjacent second linear grooves, and the groove width of the first linear groove and the groove width of the second linear groove are both smaller than the spacing between adjacent second linear grooves.

[0014] In the above technical solution, by providing multiple parallel first linear grooves and multiple parallel second linear grooves, the cross-disposition of the first and second linear grooves allows for a simple construction of multiple teeth, making the welding head easier to manufacture. Furthermore, this helps reduce the area of ​​the tooth grooves, increasing the area of ​​the teeth defined between adjacent first and second linear grooves, thereby increasing the tooth area of ​​the weld end. This allows the contour of the laser weld mark to fall more deeply into the compacted area, further alleviating the risk of thermal cracking in the laser weld mark. This, in turn, improves the electrical conductivity yield and connection strength between the tab and the conductive portion, enhancing the reliability of the battery cell.

[0015] In some embodiments, the spacing between adjacent second straight grooves is 1.5 mm to 2.5 mm.

[0016] In the above technical solution, it is helpful to improve the grip during welding to provide greater friction and to increase the tooth area ratio of the welding end.

[0017] In some embodiments, the welding end is long and narrow, the length direction of the first straight groove intersects the length direction of the welding end at an acute angle, the length direction of the second straight groove is symmetrical to the length direction of the first straight groove about the width direction of the welding end, and the tooth area accounts for 40%-50%.

[0018] In the above technical solution, the structure of the welding head is simple and easy to process, and the area occupied by the first straight groove and the second straight groove is relatively small, which can increase the tooth area ratio of the welding end, so that the tooth area ratio reaches 40%-50%, so that the contour line of the laser weld mark falls more into the compaction area, so as to improve the problem of thermal cracks in the contour of the laser weld mark to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear and the conductive part, and improving the reliability of the battery cell.

[0019] In some embodiments, the length direction of the first straight groove intersects the length direction of the welding end at 45°, and the tooth portion includes a first tooth portion defined between an adjacent first straight groove and an adjacent second straight groove, and the tooth top size of the first tooth portion in the direction of spacing between adjacent first straight grooves is 1.6mm-2mm, and the tooth top size of the first tooth portion in the direction of spacing between adjacent second straight grooves is 1.6mm-2mm.

[0020] In the above technical solution, the first tooth portion has a larger area, which is conducive to achieving a tooth area ratio of 40%-50%, and is conducive to meeting the gripping force requirements to provide greater friction. In addition, the welding head has a simple structure, is easy to process, and has a low manufacturing cost.

[0021] In some embodiments, the welding end is long and narrow, the length direction of the first linear groove is parallel to the width direction of the welding end, the length direction of the second linear groove is parallel to the length direction of the welding end, and the tooth area accounts for 50%-60%.

[0022] In the above technical solution, the structure of the welding head is simple and easy to process. The length direction of the first straight groove is set to be parallel to the width direction of the welding end, and the length direction of the second straight groove is set to be parallel to the length direction of the welding end, which is beneficial to increasing the tooth area ratio of the welding end, so that the tooth area ratio reaches 50%-60%, so that the contour line of the laser weld mark falls more into the compacted area, so as to improve the problem of thermal cracks in the contour of the laser weld mark to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear and the conductive part, and improving the reliability of the battery cell.

[0023] In some embodiments, the tooth portion includes a second tooth portion defined between adjacent first straight grooves and adjacent second straight grooves, the tooth top size of the second tooth portion in the first straight groove spacing direction is 1.5mm-2.4mm, and the tooth top size of the second tooth portion in the second straight groove spacing direction is 1.5mm-2.4mm.

[0024] In the above technical solution, the second tooth portion has a larger area, which is conducive to achieving a tooth area ratio of 50%-60%, and is conducive to meeting the gripping force requirements to provide greater friction. In addition, the welding head has a simple structure, is easy to process, and has a low manufacturing cost.

[0025] In some embodiments, the welding end is long and narrow, the length direction of the first straight groove is parallel to the width direction of the welding end, the length direction of the second straight groove is parallel to the length direction of the welding end and is located in the center of the width of the welding end, and the tooth area accounts for 60%-70%.

[0026] This technical solution reduces the proportion of tooth grooves and significantly increases the tooth area at the weld end, reaching 60%-70%. This allows the laser weld profile to fall more deeply into the compacted area, significantly improving the risk of thermal cracking within the laser weld profile. This, in turn, improves the electrical conductivity and connection strength between the tab and the conductive portion, enhancing battery cell reliability. Furthermore, due to the smaller number of second linear grooves, the tooth area defined between adjacent first and second linear grooves is larger, increasing the volume of the laser weld molten pool within the compacted area, thereby reducing pores within the molten pool and improving the laser weld's current capacity.

[0027] In some embodiments, the tooth portion includes a third tooth portion defined between adjacent first straight grooves and second straight grooves, the tooth top size of the third tooth portion in the spacing direction of the first straight grooves is 2mm-2.4mm, and the tooth top size of the third tooth portion in the length direction of the first straight grooves is 3.5mm-4.5mm.

[0028] In the above technical solution, the third teeth are elongated strips extending longitudinally along the width of the weld end. The larger area of ​​the third teeth facilitates achieving a tooth area ratio of 60%-70%, and helps meet grip requirements, thereby providing greater friction. Furthermore, the welding head has a simple structure, is easy to process, and has low manufacturing costs. When the laser weld mark is constructed as an elongated strip extending along the length of the ultrasonic weld mark, two rows of these elongated third teeth are provided at the weld end. This reduces the volume of the laser weld mark in the fluffy area across the width of the ultrasonic weld mark, thereby reducing porosity within the molten pool and improving the flow capacity of the laser weld mark.

[0029] In some embodiments, the groove width of the first straight groove is smaller than the groove width of the second straight groove.

[0030] In the above technical solution, when the laser weld mark is constructed as a long strip extending along the length direction of the ultrasonic weld mark, the groove width of the first straight groove is set to be smaller than the groove width of the second straight groove. The fluffy area corresponding to the first straight groove can be narrower, thereby reducing the fluffy area through which the two long sides of the laser weld mark contour pass, which is beneficial to improving the problem of cracking in the contour of the laser weld mark.

[0031] In some embodiments, the welding end is long and strip-shaped, and the welding tooth includes a fourth tooth portion, the length direction of the fourth tooth portion matches the length direction of the welding end, and the width direction of the fourth tooth portion matches the width direction of the welding end. There are multiple fourth tooth portions and they are spaced apart along the width direction of the welding end.

[0032] In the above technical solution, by setting the fourth tooth portion as a long strip matching the length direction of the welding end, and arranging a plurality of long strip-shaped fourth tooth portions along the width direction of the welding end, it is beneficial to increase the area of ​​a single fourth tooth portion, so as to increase the tooth area ratio of the welding end, so that the contour line of the laser weld mark falls more into the compacted area. In addition, when the laser weld mark is constructed as a long strip extending along the length direction of the ultrasonic weld mark, the two long sides of the contour of the laser weld mark can fall more into the compacted area corresponding to the fourth tooth portion, which is beneficial to improve the problem of cracking of the contour of the laser weld mark.

[0033] In some embodiments, there are two fourth tooth portions spaced apart along the width direction of the welding end, the ratio of the tooth top length of the fourth tooth portion in the length direction of the welding end to the length of the welding end is 75%-85%, the ratio of the tooth top width of the fourth tooth portion in the width direction of the welding end to half of the width of the welding end is 75%-85%, and the tooth area accounts for 70%-80%.

[0034] In the above technical solution, the area of ​​each fourth tooth can be further increased to facilitate increasing the tooth area ratio at the weld end, reaching 70%-80%. This allows the molten pool of the laser weld mark to fall more into the compacted area, thereby reducing air holes within the molten pool and improving the flow capacity of the laser weld mark. In addition, when the laser weld mark is constructed as an elongated strip extending along the length of the ultrasonic weld mark, the two long sides of the laser weld mark can fall into the compacted areas corresponding to the two fourth teeth, respectively. This facilitates the placement of the laser weld mark and improves the problem of cracking in the laser weld mark profile.

[0035] In some embodiments, each long side of the fourth tooth portion has a plurality of protrusions spaced apart along the length direction of the welding end, and the protrusions protrude toward the width direction of the welding end.

[0036] In the above technical solution, each long side of the fourth tooth portion is uneven, which helps to improve the grip during welding to provide greater friction, so that the fourth tooth portion can effectively compact the pole piece and improve the compaction rate of the compaction area corresponding to the fourth tooth portion, which can further improve the problem of cracks in the outline of the laser weld mark.

[0037] In some embodiments, the welding tooth also includes a plurality of fifth teeth arranged between the two fourth teeth and spaced apart along the length direction of the welding end, the convex portions of the two fourth teeth close to each other are positioned opposite to each other, and two opposite convex portions are respectively arranged between each adjacent two fifth teeth, and the contour line of the fourth tooth matches the contour line of the fifth tooth.

[0038] In the above technical solution, the welding end can be further utilized to construct the welding teeth, increase the area of ​​the fourth tooth portion and the fifth tooth portion, and increase the tooth area ratio of the welding end. When the two long sides of the laser weld mark correspond to the compaction areas corresponding to the two fourth tooth portions, the laser weld mark can also cover at least part of the compaction areas corresponding to multiple fifth tooth portions, thereby facilitating the increase of the portion of the laser weld mark falling in the compaction area, further improving the problem of pores appearing in the molten pool of the laser weld mark, and further improving the conductivity yield of the converged portion and the conductive portion.

[0039] In some embodiments, the welding tooth includes a plurality of sixth teeth, the sixth teeth are multiple and spaced apart and arranged around the two fourth teeth, and the contour lines of the fourth teeth match the contour lines of the sixth teeth.

[0040] In the above technical solution, multiple sixth teeth are arranged around the two fourth teeth, and since the contour line of the sixth tooth matches the contour line of the fourth tooth, that is, the protruding position of the contour of the fourth tooth corresponds to the concave position of the contour of the sixth tooth, it helps to improve the grip during welding to provide greater friction, so that the fourth tooth can effectively compact the tab sheet, improve the compaction rate of the compaction area corresponding to the fourth tooth, and further improve the problem of cracks in the contour of the laser weld mark.

[0041] In some embodiments, a dimension K1 of the protrusion along the length direction of the welding end is 1.5 mm to 2.4 mm, and a dimension K2 of the protrusion along the width direction of the welding end is 0.2 mm to 1.2 mm.

[0042] In the above technical solution, by setting the size of the protrusion as above, it is helpful to improve the grip during welding to provide greater friction, so that the fourth tooth portion can effectively compact the tab.

[0043] In some embodiments, the groove width of the tooth groove is 0.2 mm-0.6 mm.

[0044] In the above technical solution, the groove width of the tooth groove is small, so that the proportion of the tooth groove on the welding end can be reduced to increase the proportion of the welding teeth, thereby increasing the proportion of the compacted area on the converged part.

[0045] In some embodiments, a tooth tip dimension of the tooth portion in a normal direction of an adjacent tooth groove is greater than or equal to 1.5 mm.

[0046] In the above technical solution, the area of ​​a single tooth portion is not too small, which is beneficial to improving the compaction rate of the compaction area.

[0047] In some embodiments, the tooth height of the tooth portion is less than or equal to 2.5 mm, and the projection distance between the tooth top and the tooth bottom of the tooth portion is 0.1 mm-0.2 mm.

[0048] In the above technical solution, the side surface of the tooth portion has a certain inclination, which is convenient for improving the compaction rate and reducing the sharpness of the edge of the tooth portion to improve the problem of scratching the tab sheet.

[0049] In some embodiments, the edge of the welding end is rounded, and the rounded radius is 0.5 mm-2 mm.

[0050] In the above technical solution, during the ultrasonic welding process, the problem of the edge of the welding end scratching the edge of the pole tab can be improved, which is conducive to the smooth progress of welding and improves the connection reliability and conductivity between the pole tab and the conductive part.

[0051] In a second aspect, an embodiment of the present application further provides an ultrasonic welding device, comprising a drive cylinder, a welding seat, and a welding head of any of the above-mentioned schemes, wherein the drive cylinder is arranged on a side of the welding head away from the welding seat, and is used to drive the welding head to move toward the welding seat.

[0052] In the above technical solution, since the welding head according to the embodiment of the present application is conducive to increasing the area of ​​the compacted region in the ultrasonic weld mark, the weld mark welded by the ultrasonic welding device has a larger compacted area, which is conducive to improving the subsequent laser welding effect of the pole ear and the conductive part.

[0053] In some embodiments, the driving cylinder is a pneumatic cylinder, and the diameter of the pneumatic cylinder is greater than 125 mm.

[0054] In the above technical solution, the welding pressure can be increased, thereby increasing the compaction rate of the compaction area, improving the problem of thermal cracks in the outline of the laser weld mark, improving the conductivity yield and connection strength between the pole ear and the conductive part, and reducing the pores in the molten pool of the laser weld mark, improving the current flow capacity of the laser weld mark, and improving the reliability of the battery cell.

[0055] In some embodiments, the cylinder has a diameter of 160 mm or 200 mm.

[0056] In the above technical solution, the cylinder is relatively easy to process and can work, and the compaction rate of the compaction area is high, which can effectively improve the problem of thermal cracks in the outline of the laser weld mark, improve the conductivity yield and connection strength of the pole ear and the conductive part, and reduce the pores in the molten pool of the laser weld mark, improve the current flow capacity of the laser weld mark, and enhance the reliability of the battery cell.

[0057] In a third aspect, an embodiment of the present application further provides a battery cell, comprising: a shell component, a pole component and an electrode assembly, the pole component being arranged in the shell component, the pole component including a conductive portion, the electrode assembly being accommodated in the shell component and including a pole ear portion, the pole ear portion including a plurality of pole ear sheets arranged in a stacked manner, the plurality of pole ear sheets being connected to form a gathered portion, the gathered portion being overlapped and connected with the conductive portion to form a connecting portion; wherein the gathered portion includes a compacted area, the thickness of the compacted area is less than the stacking thickness of the plurality of pole ear sheets in the pole ear portion, the connecting portion includes a first part formed in the gathered portion, at least most of the contour line of the first part is located in the compacted area, the gathered portion is processed by an ultrasonic welding device including any of the above-mentioned schemes and the compacted area is processed by welding teeth.

[0058] In the above technical solution, since at least part of the contour line of the portion of the connection portion formed on the gathered portion is arranged in the compacted area, the multiple layers of the pole tab sheets in the compacted area are very tightly combined together, which is beneficial to improving the problem of cracks in the contour of the connection portion, improving the conductive yield and connection strength between the pole tab portion and the conductive portion, and enhancing the current carrying capacity and reliability of the battery cell.

[0059] In some embodiments, the connecting portion extends from the outer surface of the gathered portion toward the conductive portion, and the first portion includes a surface portion formed on the outer surface of the gathered portion, with more than 60% of the contour of the surface portion falling within the compacted area.

[0060] In the above technical solution, by setting the direction of extension of the connecting portion from the gathered portion toward the conductive portion, the welding head is easily aligned with the gathered portion. This allows the welding head to rationally design the welding trajectory based on the distribution of the compacted and bulky areas on the gathered portion, and accurately weld along the welding trajectory. This ensures that at least a majority of the contour of the portion of the connecting portion formed on the gathered portion is reliably located in the compacted area, effectively improving the conductivity yield and connection strength between the tab and the conductive portion, and enhancing the current carrying capacity and reliability of the battery cell. Furthermore, by setting the contour of the surface portion to have at least 60% of its surface portion fall within the compacted area, the problem of cracking in the weld contour of the connecting portion on the gathered portion surface can be further alleviated. Furthermore, since the connecting portion extends from the outer surface of the gathered portion toward the conductive portion, the contour of the inner portion can extend from the contour of the surface portion toward the conductive portion. When at least 60% of the contour of the surface portion falls within the compacted area, the proportion of the contour of the inner portion falling within the compacted area relative to the bulky area is further increased, thereby further improving the overall problem of cracking in the contour of the first portion of the connecting portion formed on the gathered portion.

[0061] In some embodiments, the compaction rate of the compacted region is greater than or equal to 6%.

[0062] In the above technical solution, by setting the compaction rate of the compaction area to be greater than or equal to 6%, the interlayer gap in the compaction area can be reduced, and the part of the connection part that enters the compaction area is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connection part, as well as the reliability and conductivity yield of the connection part connecting the conductive part and the gathered part.

[0063] In some embodiments, the compaction rate of the compacted region is greater than or equal to 12%.

[0064] In the above technical solution, by setting the compaction rate of the compaction area to be greater than or equal to 12%, the gap in the compaction area can be further reduced, so that there is almost no gap in the compaction area, and the part where the connecting part enters the compaction area is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connection part, as well as the reliability and conductivity yield of the connection part connecting the conductive part and the gathered part.

[0065] In a fourth aspect, an embodiment of the present application further provides a battery comprising a battery cell according to any of the above solutions.

[0066] In the above technical solution, since the reliability of the battery cell according to the embodiment of the present application is improved, it is beneficial to improve the reliability of the battery.

[0067] In a fifth aspect, an embodiment of the present application further provides an electrical device comprising a battery according to any of the above-mentioned solutions.

[0068] In the above technical solution, since the reliability of the battery is improved, it is beneficial to improve the working power performance of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0070] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0071] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0072] FIG3 is a perspective view of a battery cell provided in some embodiments of the present application;

[0073] FIG4 is a top view of a battery cell provided in some embodiments of the present application;

[0074] FIG5 is a cross-sectional view along line AA in FIG4 ;

[0075] FIG6 is a partial enlarged view of portion B in FIG5 ;

[0076] FIG7 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0077] FIG8 is a schematic diagram of ultrasonic pre-welding of a tab portion by an ultrasonic welding device provided in some embodiments of the present application;

[0078] FIG9 is a partial enlarged view of portion C in FIG8 ;

[0079] FIG10 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0080] FIG11 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0081] FIG12 is a partial schematic diagram of a welding head provided in some embodiments of the present application;

[0082] FIG13 is a schematic diagram of a welding end of a welding head provided in some embodiments of the present application;

[0083] FIG14 is a schematic diagram of a welding end of a welding head provided in some other embodiments of the present application;

[0084] FIG15 is a schematic diagram of a welding end of a welding head provided in some other embodiments of the present application;

[0085] FIG16 is a schematic diagram of a welding end of a welding head provided in some other embodiments of the present application;

[0086] FIG17 is a schematic diagram of welding a gathered portion and a conductive portion according to some embodiments of the present application;

[0087] FIG18 is a front view of an ultrasonic welding device provided in some embodiments of the present application;

[0088] FIG19 is a left side view of the ultrasonic welding device shown in FIG18;

[0089] FIG20 is a partial cross-sectional morphology diagram of the gathered portion of Comparative Example 1;

[0090] FIG21 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion of Comparative Example 1 after laser welding;

[0091] FIG22 is a partial cross-sectional morphology diagram of the gathered portion of Comparative Example 2;

[0092] FIG23 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion of Comparative Example 2 after laser welding;

[0093] FIG24 is a partial cross-sectional morphology diagram of the convergent portion of Comparative Example 3;

[0094] FIG25 is a partial cross-sectional morphology of the gathered portion and the conductive portion of Comparative Example 3 after laser welding;

[0095] FIG26 is a partial cross-sectional topographic view of the gathered portion of Example 1;

[0096] FIG27 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 1;

[0097] FIG28 is a partial cross-sectional topographic view of the gathered portion of Example 2;

[0098] FIG29 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 2;

[0099] FIG30 is a partial cross-sectional topography of the gathered portion of Example 3;

[0100] FIG31 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 3;

[0101] FIG32 is a partial cross-sectional topography of the gathered portion of Example 4;

[0102] FIG33 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding of the fourth embodiment;

[0103] FIG34 is a topographical diagram of an ultrasonic weld mark produced by the welding head shown in FIG13;

[0104] FIG35 is a cross-sectional topography of the ultrasonic weld mark shown in FIG34;

[0105] FIG36 is a topographical diagram of an ultrasonic weld mark produced by the welding head shown in FIG14 ;

[0106] FIG37 is a cross-sectional topography of the ultrasonic weld mark shown in FIG36 ;

[0107] FIG38 is a topographical diagram of an ultrasonic weld mark produced by the welding head shown in FIG15 ;

[0108] FIG39 is a cross-sectional topography of the ultrasonic weld mark shown in FIG38;

[0109] FIG40 is a topographical diagram of an ultrasonic weld mark produced by the welding head shown in FIG16;

[0110] FIG41 is a cross-sectional topography diagram of the ultrasonic weld mark shown in FIG40.

[0111] Reference numerals:

[0112] Vehicles 1000;

[0113] Battery 100; Controller 200; Motor 300;

[0114] Box body 101; first box body 1011; second box body 1012;

[0115] Battery cell 102; first direction X; second direction Y; third direction Z;

[0116] Fourth direction E; fifth direction F; sixth direction M; seventh direction N;

[0117] Housing component 1; first housing wall 11; accommodating cavity 12;

[0118] Pole component 2; conductive portion 20; pole body 21;

[0119] Electrode assembly 3; active material coating portion 31; pole ear portion 32; pole ear sheet 320;

[0120] Gathered portion 321; compacted area 3211; fluffy area 3212;

[0121] Connecting portion 4; first portion 41; surface portion 411; contour line 4x of surface portion 411;

[0122] The long side of the surface part is 4x1; the short side of the surface part is 4x2;

[0123] Inner portion 412; outline 4y of inner portion 412; second portion 42;

[0124] First connecting portion 4a; second connecting portion 4b; third connecting portion 4c;

[0125] Ultrasonic welding device 2000;

[0126] Welding head 400; welding end 401; welding teeth 5; tooth portion 51;

[0127] First tooth portion 511; second tooth portion 512; third tooth portion 513;

[0128] Fourth tooth portion 514; convex portion 5141; fifth tooth portion 515; sixth tooth portion 516;

[0129] First sub-tooth 5161; second sub-tooth 5162;

[0130] Tooth groove 6; first straight groove 61; second straight groove 62;

[0131] First separation groove 63; second separation groove 64;

[0132] Welding seat 500; driving cylinder 600. DETAILED DESCRIPTION

[0133] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0134] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0135] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0136] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0137] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0138] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0139] The term "plurality" used in this application refers to two or more (including two).

[0140] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0141] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery module generally includes multiple battery cells. A battery pack generally includes a casing for enclosing one or more battery cells or one or more battery modules. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0142] A battery cell consists of a housing, an electrode assembly, and an electrolyte. The housing houses the electrode assembly and electrolyte. The housing contains at least one electrode assembly, which consists of a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly can be a wound or stacked structure. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets.

[0143] A positive electrode sheet generally includes a positive current collector and a positive active material layer. The positive active material layer is directly or indirectly coated on the positive current collector. The uncoated positive current collector protrudes from the coated positive current collector, serving as the positive tab. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, and the positive active material layer can be made of lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide.

[0144] A negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is directly or indirectly coated on the negative electrode current collector. The negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector not coated with the negative electrode active material layer serves as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material layer can be made of carbon, silicon, or other materials.

[0145] To ensure high current flow without melting, multiple positive electrode tabs are stacked together to form the positive electrode tab, while multiple negative electrode tabs are stacked together to form the negative electrode tab. A post is provided on the housing, with the positive electrode tab electrically connected to the positive post and the negative electrode tab electrically connected to the negative post.

[0146] In related technologies, ultrasonic welding is used to connect multiple tabs in the tab section, forming an ultrasonic weld mark. This weld mark is then laser welded to the conductive portion of the pole post, achieving connection and electrical continuity between the electrode assembly and the pole post. However, the laser weld profile is susceptible to thermal cracking, which affects the conductivity yield and connection strength between the tab and the conductive portion, and thus the reliability of the battery cell.

[0147] To this end, an embodiment of the present application proposes a welding head 400, wherein the welding end of the welding head 400 has welding teeth and tooth grooves, and the welding teeth are separated by the tooth grooves into multiple teeth arranged at intervals, and the tooth area of ​​the welding end accounts for greater than or equal to 40%. Therefore, by setting the tooth area ratio of the welding end to be no less than 40%, the area ratio of the compacted area in the ultrasonic weld mark can be increased, so that the contour of the laser weld can fall more into the compacted area. Since the multiple layers of the tab sheets in the compacted area can be very tightly combined, it is beneficial to improve the problem of thermal cracking deterioration in the contour of the laser weld, thereby improving the conductivity yield and connection strength between the tab and the conductive part, and improving the reliability of the battery cell.

[0148] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0149] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0150] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0151] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0152] Please refer to Figure 2, which is an exploded view of the structure of the battery 100 provided in some embodiments of the present application. The battery 100 includes a box body 101 and a plurality of battery cells 102, and the battery cells 102 are accommodated in the box body 101. The box body 101 is used to provide an assembly space for the battery cells 102, and the box body 101 can adopt a variety of structures. In some embodiments, the box body 101 may include a first box body 1011 and a second box body 1012, and the first box body 1011 and the second box body 1012 cover each other, and the first box body 1011 and the second box body 1012 jointly define an assembly space for accommodating the battery cells 102. The second box body 1012 can be a hollow structure with one end open, and the first box body 1011 can be a plate-shaped cover structure, with the first box body 1011 covering the open side of the second box body 1012, so that the first box body 1011 and the second box body 1012 jointly define an assembly space; the first box body 1011 and the second box body 1012 can also be hollow structures with one side open, with the open side of the first box body 1011 covering the open side of the second box body 1012. Of course, the box body 101 formed by the first box body 1011 and the second box body 1012 can be of various shapes, such as a cylinder, a cuboid, etc.

[0153] In the battery 100, multiple battery cells 102 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections within the multiple battery cells 102. Multiple battery cells 102 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 102 is housed within the housing 101. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 102 in series, in parallel, or in a hybrid configuration to form a battery module. The multiple battery modules are then connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 101. The battery 100 may also include other structures, such as a busbar assembly for electrically welding the multiple battery cells 102 together.

[0154] Each battery cell 102 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 102 can be cylindrical, flat, or rectangular. For example, referring to the embodiment shown in FIG3 , the length of the battery cell 102 is a first direction X, the width of the battery cell 102 is a second direction Y, and the height of the battery cell 102 is a third direction Z. The first direction X, the second direction Y, and the third direction Z are mutually perpendicular.

[0155] Please refer to Figures 3-7. Figure 3 is a perspective view of a battery cell 102 according to some embodiments of the present application. Figure 4 is a top view of the battery cell 102 shown in Figure 3. Figure 5 is a cross-sectional view taken along line AA in Figure 4. Figure 6 is a partial enlarged view of section B in Figure 5. Figure 7 is a partial cross-sectional view of the connection between the conductive portion 20 and the retracted portion 321 according to some embodiments of the present application. In some embodiments of the present application, the battery cell 102 includes: a housing component 1, a post component 2, and an electrode assembly 3. The post component 2 is disposed in the housing component 1 and includes a conductive portion 20. The electrode assembly 3 is housed in the housing component 1 and includes a tab portion 32. The tab portion 32 includes a plurality of tab sheets 320 stacked in a stack. The plurality of tab sheets 320 are connected to form a retracted portion 321. The retracted portion 321 overlaps and connects with the conductive portion 20 to form a connecting portion 4.

[0156] For example, in conjunction with Figures 3 to 6, the shell component 1 may include a first shell wall 11, and the pole component 2 is arranged on the first shell wall 11. The structure of the shell component 1 is not limited. For example, the shell component 1 may include a shell body and a shell cover, the shell body defines a cavity with one end closed and the other end open, and the shell cover is provided on the open end of the shell body, wherein the shell cover can serve as the first shell wall 11, or the end wall surface of the shell body opposite to the shell cover can also serve as the first shell wall 11. For another example, the shell component 1 may include two half shells arranged in opposition, each half shell defining a cavity open toward the other half shell, and the end wall surface of one half shell away from the other half shell serves as the first shell wall 11.

[0157] 5 and 6 , the pole component 2 includes a conductive portion 20, which is the portion of the pole component 2 used to connect to the electrode assembly 3. For example, the conductive portion 20 may be the pole body 21. In this case, the gathered portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the pole body 21. For another example, the conductive portion 20 may also be an adapter plate connected to the pole body 21. In this case, the gathered portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the adapter plate, which is electrically connected to the pole body 21, thereby indirectly electrically connecting the gathered portion 321 to the pole body 21 via the adapter plate. To simplify the description, the following description mainly uses the pole body 21 as an example for the conductive portion 20.

[0158] 5 and 6 , the electrode assembly 3 includes an active material coating portion 31 housed within the housing component 1, and a pole ear portion 32 connected to the active material coating portion 31. Exemplarily, a housing cavity 12 is formed within the housing component 1, the active material coating portion 31 is housed within the housing cavity 12, the pole body 21 is passed through the first shell wall 11, and the pole ear portion 32 is welded to the pole body 21. The pole ear portion 32 is directly electrically connected to the pole body 21, so that the pole ear portion 32 is electrically connected between the active material coating portion 31 and the pole body 21.

[0159] For example, referring to Figures 6 and 7 , the multiple tabs 320 in the tab portion 32 are stacked, and the multiple tabs 320 are ultrasonically welded to form a gathered portion 321. That is, the portion where the multiple tabs 320 are connected together by ultrasonic welding is an ultrasonic weld mark, which constitutes the gathered portion 321. Therefore, the multiple tabs 320 in the gathered portion 321 are not only stacked but also connected. The thickness side surface of the gathered portion 321 faces the conductive portion 20 and is disposed on the conductive portion 20 to achieve overlap between the gathered portion 321 and the conductive portion 20. The gathered portion 321 and the conductive portion 20 are connected together by laser welding, and the laser weld forms the connecting portion 4 connecting the conductive portion 20 and the gathered portion 321.

[0160] In the embodiment of the present application, in combination with Figures 7 to 9, the gathered portion 321 includes a compacted area 3211, and the thickness T1 of the compacted area 3211 is less than the theoretical thickness T2 of the pole ear portion 32. Therefore, since the thickness T1 of the compacted area 3211 of the gathered portion 321 is less than the theoretical thickness T2 of the pole ear portion 32, it means that the pole ear sheet 320 in the compacted area 3211 is compressed and yielded and plastically deformed, the thickness of the pole ear sheet 320 is thinned, and the multiple layers of pole ear sheets 320 in the compacted area 3211 are tightly combined together with no or almost no gaps between layers, and the compaction rate of the gathered portion 321 is greater than 0%.

[0161] The "compaction rate" of the gathered portion 321 refers to the ratio of the difference between the theoretical thickness T2 of the tab portion 32 and the thickness T1 of the compacted region 3211 to the theoretical thickness T2 of the tab portion 32, i.e., (T2-T1) / T2. The theoretical thickness T2 refers to the stacked thickness of the multiple tab sheets 320 in the tab portion 32, i.e., the thickness of the tab sheets 320 when they are uncompressed and stacked together without gaps. For example, if the thickness of a single tab sheet 320 is a (i.e., a is the thickness of a single layer of foil), and there are b layers of tab sheets 320 stacked in the tab portion 32 (i.e., b is the number of foil layers), then the stacked thickness of the multiple tab sheets 320 in the tab portion 32 is a×b, and therefore the theoretical thickness T2 of the tab portion 32 is a×b.

[0162] For example, in combination with Figures 8 and 9, ultrasonic welding is used to process the gathered portion 321. The welding head 400 used in the ultrasonic welding process has welding teeth 5 and tooth grooves 6. The welding teeth 5 are separated by the tooth grooves 6 into a plurality of tooth portions 51 arranged at intervals, that is, the tooth grooves 6 are the inter-tooth gaps between the multiple tooth portions 51 of the welding teeth 5. After welding, the area on the gathered portion 321 corresponding to the tooth portion 51 is the compacted area 3211, and the area on the gathered portion 321 corresponding to the tooth grooves 6 is the fluffy area 3212. The multi-layer pole tabs 320 in the compacted area 3211 are effectively welded and fused together, and there is no or almost no interlayer gap between the foils. The multi-layer pole tabs 320 in the fluffy area 3212 are not effectively fused together, and there are interlayer gaps between the multi-layer pole tabs 320.

[0163] In the embodiment of the present application, please refer to Figures 6 and 7 again. The connecting portion 4 formed by the laser weld includes a first portion 41 formed on the gathering portion 321, and a second portion 42 formed on the conductive portion 20. It can be understood that since the connecting portion 4 needs to connect the conductive portion 20 and the gathering portion 321, a portion of the connecting portion 4 will be formed on the gathering portion 321, which is the first portion 41, and the remaining portion will be formed on the conductive portion 20, which is the second portion 42.

[0164] For example, with reference to FIG7 , when laser welding is performed from the side of the gathered portion 321 facing away from the conductive portion 20, the first portion 41 of the connecting portion 4 formed on the gathered portion 321 may include: a surface portion 411 formed on the outer surface of the gathered portion 321, and an inner portion 412 formed within the gathered portion 321. In this case, the outline 4x of the surface portion 411 and the outline 4y of the inner portion 412 constitute the outline of the first portion 41. Alternatively, if laser welding is performed from the side of the conductive portion 20 facing away from the gathered portion 321, the first portion 41 of the connecting portion 4 formed on the gathered portion 321 may include only: the inner portion 412 formed within the gathered portion 321. In this case, the outline 4y of the inner portion 412 constitutes the outline of the first portion 41.

[0165] For example, when the connection portion 4 is a long strip-shaped laser weld, the outline 4x of the surface portion 411 may be a rectangular frame surrounded by two long sides 4x1 and two short sides 4x2.

[0166] The contour of the first portion 41 can fall entirely within the compacted region 3211, that is, the contour of the portion of the connecting portion 4 formed on the gathered portion 321 can be entirely located in the compacted region 3211. Alternatively, the contour of the first portion 41 can also partially fall within the compacted region 3211 and the remainder fall within the puffy region 3212, that is, the contour of the portion of the connecting portion 4 formed on the gathered portion 321 can partially fall within the compacted region 3211, and the remainder fall within the puffy region 3212. Because the multiple layers of tab sheets 320 are very tightly bonded together in the compacted region 3211, with little or no interlayer gaps, the contour falling within the compacted region 3211 is less likely to develop thermal cracks, resulting in a good electrical conductivity yield and connection reliability between the conductive portion 20 and the gathered portion 32.

[0167] In an embodiment of the present application, when the connection portion 4 is a laser weld, it may include only one weld, which is completed in one welding, or it may include multiple welds superimposed on each other, which are completed in multiple weldings. In this case, the total weld formed by the fusion of the multiple welds constitutes the connection portion 4. For example, in conjunction with Figure 10, the laser weld may include a base weld (such as the first connection portion 4a marked in Figure 10), a main weld (such as the second connection portion 4b marked in Figure 10), and a repair weld (such as the third connection portion 4c marked in the figure) welded in sequence. In this case, the total weld formed by the fusion of the three welds constitutes the connection portion 4. For another example, in conjunction with Figure 11, the repair weld may be omitted, and the base weld (such as the first connection portion 4a marked in Figure 11) and the main weld (such as the second connection portion 4b marked in Figure 11) may be welded in sequence. In this case, the total weld formed by the fusion of the two welds constitutes the connection portion 4. For another example, referring to FIG7 , the repair weld and the base weld may be omitted, and only one main weld (eg, the second connection portion 4 b marked in FIG7 ) may be welded, and the connection portion 4 may be formed by the main weld.

[0168] In conjunction with Figures 12 and 13 , an embodiment of the present application provides a welding head 400 , wherein a welding end 401 of the welding head 400 includes welding teeth 5 and tooth grooves 6 . The welding teeth 5 are separated by the tooth grooves 6 into a plurality of spaced-apart teeth 51 . The tooth area ratio of the welding end 401 is greater than or equal to 40%. It is worth noting that the "tooth area ratio of the welding end 401" refers to the ratio of the area of ​​the welding teeth 5 to the area of ​​the welding end 401 , or the ratio of the sum of the areas of all the teeth 51 to the area of ​​the welding end 401 , or the ratio of the difference between the toothless area of ​​the welding end 401 and the tooth groove area of ​​the welding end to the toothless area of ​​the welding end 401 .

[0169] Therefore, by setting the tooth area ratio of the welding end 401 to no less than 40%, the area ratio of the compacted area 3211 in the ultrasonic weld mark can be increased, so that the contour line of the laser weld falls more into the compacted area 3211, so as to improve the problem of thermal cracks in the contour of the laser weld to a greater extent, thereby improving the conductive yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0170] In some embodiments of the present application, as shown in Figures 12 and 13, the tooth groove 6 includes a first linear groove 61 and a second linear groove 62 arranged in a cross-arrangement. The first linear grooves 61 are multiple and arranged in parallel, and a tooth portion 51 is defined between adjacent first linear grooves 61 and second linear grooves 62. For example, because adjacent first linear grooves 61 are arranged in parallel, the tooth portion 51 defined between two adjacent first linear grooves 61 and second linear grooves 62 can be polygonal, and the two adjacent first linear grooves 61 and the second linear groove 62 intersecting the two first linear grooves 61 can constitute the three sides of a tooth portion 51. Thus, by dividing the welding teeth 5 by linear grooves, the tooth grooves 6 are easy to process, which facilitates reducing the processing cost of the welding head 400 and improving the processing efficiency of the welding head 400.

[0171] As shown in FIG13 , the groove width W1 of the first linear groove 61 and the groove width W2 of the second linear groove 62 are both smaller than the spacing D1 between adjacent first linear grooves 61. The dimension of the tooth portion 51 defined between adjacent first linear grooves 61 and second linear grooves 62 in the direction of spacing between the first linear grooves 61 is equal to the spacing D1 between adjacent first linear grooves 61, and is larger than both the groove width W1 of the first linear groove 61 and the groove width W2 of the second linear groove 62.

[0172] This is beneficial to reducing the area ratio of the tooth groove 6 and increasing the area of ​​the tooth portion 51 defined between the adjacent first straight groove 61 and the second straight groove 62, thereby helping to increase the tooth area ratio of the welding end 401, so that the contour line of the laser weld falls more into the compacted area 3211, further improving the problem of thermal cracks in the contour of the laser weld, thereby improving the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0173] In some embodiments of the present application, as shown in FIG13 , the spacing D1 between adjacent first linear grooves 61 is 1.5 mm to 2.5 mm. For example, the spacing D1 between adjacent first linear grooves 61 can be 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, and so on. Thus, the spacing D1 between adjacent first linear grooves 61 is not too large, which is beneficial for improving the grip during welding. The spacing D1 between adjacent first linear grooves 61 is not too small, so that the size of the tooth portion 51 defined between the adjacent first linear grooves 61 and the second linear grooves 62 is not too small, thereby facilitating an increase in the tooth area ratio of the welding end 401.

[0174] In some embodiments of the present application, as shown in FIG13 , a plurality of second linear grooves 62 are arranged in parallel, and a tooth portion 51 is defined between adjacent first linear grooves 61 and adjacent second linear grooves 62. For example, since adjacent first linear grooves 61 are arranged in parallel, adjacent second linear grooves 62 are also arranged in parallel, and the tooth portion 51 defined between two adjacent first linear grooves 61 and two adjacent second linear grooves 62 can be a quadrilateral, and two adjacent first linear grooves 61 and two adjacent second linear grooves 62 that intersect with the two first linear grooves 61 can constitute the four sides of a tooth portion 51. Thus, by providing a plurality of parallel first linear grooves 61 and a plurality of parallel second linear grooves 62, and since the first linear grooves 61 and the second linear grooves 62 are arranged in an intersecting manner, a plurality of tooth portions 51 can be simply constructed, making the welding head 400 easy to process.

[0175] As shown in FIG13 , the groove width W1 of the first linear groove 61 and the groove width W2 of the second linear groove 62 are both smaller than the spacing D2 between adjacent second linear grooves 62. Therefore, the dimension of the tooth portion 51 defined between adjacent first linear grooves 61 and adjacent second linear grooves 62 in the direction of spacing between the second linear grooves 62 is equal to the spacing D2 between adjacent second linear grooves 62, which is larger than both the groove width W1 of the first linear groove 61 and the groove width W2 of the second linear groove 62.

[0176] This is beneficial to reducing the area ratio of the tooth groove 6 and increasing the area of ​​the tooth portion 51 defined between the adjacent first straight groove 61 and the adjacent second straight groove 62, thereby helping to increase the tooth area ratio of the welding end 401, so that the contour line of the laser weld falls more into the compacted area 3211, further improving the problem of thermal cracks in the contour of the laser weld, thereby improving the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0177] In some embodiments of the present application, as shown in FIG13 , the spacing D2 between adjacent second linear grooves 62 is 1.5 mm to 2.5 mm. For example, the spacing D2 between adjacent second linear grooves 62 can be 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, and so on. Thus, the spacing D2 between adjacent second linear grooves 62 is not too large, which is beneficial for improving the grip during welding. The spacing D2 between adjacent second linear grooves 62 is not too small, so that the size of the tooth portion 51 defined between adjacent first linear grooves 61 and adjacent second linear grooves 62 is not too small, thereby facilitating an increase in the tooth area ratio of the welding end 401.

[0178] In some embodiments of the present application, as shown in Figure 13, the welding end 401 is long and narrow, the length direction of the first straight groove 61 intersects the length direction of the welding end 401 at an acute angle a1, and the length direction of the second straight groove 62 is symmetrical with the length direction of the first straight groove 61 about the width direction of the welding end 401. Therefore, the angle a2 and a1 at which the length direction of the second straight groove 62 intersects the length direction of the welding end 401 are equal, and the tooth area accounts for 40%-50%, for example, the tooth area accounts for 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0179] For example, as shown in FIG13 , the length direction of the welding end 401 extends along the fourth direction E, the width direction of the welding end 401 extends along the fifth direction F, the length direction of the first linear groove 61 extends along the sixth direction M, and the length direction of the second linear groove 62 extends along the seventh direction N. The sixth direction M intersects the fourth direction E at an acute angle, and the seventh direction N and the sixth direction M are axisymmetric about the fifth direction F. Thus, the plurality of teeth 51 defined by the plurality of first linear grooves 61 and the plurality of second linear grooves 62 can present an oblique grid form.

[0180] Therefore, the structure of the welding head 400 is simple and easy to process, and the area occupied by the first straight groove 61 and the second straight groove 62 is relatively small, which can increase the tooth area ratio of the welding end 401, so that the tooth area ratio reaches 40%-50%, so that the contour line of the laser weld falls more into the compacted area 3211, so as to improve the problem of thermal cracks in the contour of the laser weld to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear part 32 and the conductive part 20, and improving the reliability of the battery cell 102.

[0181] In addition, when the laser weld is constructed as a long strip extending along the length direction of the ultrasonic weld mark (that is, the length direction of the welding end 401), the length direction of the second straight groove 62 is set to be symmetrical with the length direction of the first straight groove 61 about the width direction of the welding end 401. Compared with the comparative scheme that also achieves a tooth area ratio of 40%-50% but does not set the length direction of the second straight groove 62 to be symmetrical with the length direction of the first straight groove 61 about the width direction of the welding end 401, it is beneficial for the two long sides of the laser weld profile to pass through the fluffy area 3212 less frequently, which is beneficial to improving the problem of thermal cracks in the laser weld profile.

[0182] For example, referring to FIG13 , the length direction of the first linear groove 61 (e.g., the sixth direction M) intersects the length direction of the welding end 401 (e.g., the fourth direction E) at 45°. The tooth portion 51 defined between the adjacent first linear groove 61 and the adjacent second linear groove 62 is the first tooth portion 511. The tooth top dimension S1 of the first tooth portion 511 in the direction of spacing between the first linear grooves 61 is 1.6 mm to 2 mm, and the tooth top dimension S2 of the first tooth portion 511 in the direction of spacing between the second linear grooves 62 is 1.6 mm to 2 mm. As a result, the area of ​​the first tooth portion 511 is relatively large, which is conducive to achieving a tooth area ratio of 40% to 50%, and is conducive to meeting the grip requirements to provide greater friction. Moreover, the welding head 400 has a simple structure, is easy to process, and has low manufacturing costs.

[0183] In some other embodiments of the present application, as shown in Figure 14, the welding end 401 is long and narrow, the length direction of the first straight groove 61 is parallel to the width direction of the welding end 401, the length direction of the second straight groove 62 is parallel to the length direction of the welding end 401, and the tooth area accounts for 50%-60%, for example, the tooth area accounts for 50%, 52%, 54%, 56%, 58%, 60%, etc.

[0184] For example, as shown in FIG14 , the length direction of the welding end 401 extends along the fourth direction E, the width direction of the welding end 401 extends along the fifth direction F, the length direction of the first linear groove 61 is parallel to the fifth direction F, and the length direction of the second linear groove 62 is parallel to the fourth direction E. Thus, the plurality of teeth 51 defined by the plurality of first linear grooves 61 and the plurality of second linear grooves 62 can present a grid pattern.

[0185] Therefore, the structure of the welding head 400 is simple and easy to process. The length direction of the first straight groove 61 is set to be parallel to the width direction of the welding end 401, and the length direction of the second straight groove 62 is set to be parallel to the length direction of the welding end 401. This is beneficial to increasing the tooth area ratio of the welding end 401, so that the tooth area ratio reaches 50%-60%, so that the contour line of the laser weld falls more into the compacted area 3211, so as to improve the problem of thermal cracks in the contour of the laser weld to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear part 32 and the conductive part 20, and improving the reliability of the battery cell 102.

[0186] In addition, when the laser weld is constructed as a long strip extending along the length direction of the ultrasonic weld mark (that is, the length direction of the welding end 401), the length direction of the first straight groove 61 is set to be parallel to the width direction of the welding end 401, and the length direction of the second straight groove 62 is set to be parallel to the length direction of the welding end 401. Compared with the comparative scheme that also achieves a tooth area ratio of 50%-60%, but does not set the length direction of the first straight groove 61 to be parallel to the width direction of the welding end 401 and the length direction of the second straight groove 62 to be parallel to the length direction of the welding end 401, the two long sides of the contour of the laser weld can pass through the fluffy area 3212 less frequently, which is beneficial to improving the problem of thermal cracks in the contour of the laser weld and the problem of debris generated at the edge of the laser weld.

[0187] For example, referring to FIG. 14 , the tooth portion 51 includes a second tooth portion 512 defined between adjacent first linear grooves 61 and adjacent second linear grooves 62. The tooth top dimension S3 of the second tooth portion 512 in the direction of spacing between the first linear grooves 61 is 1.5 mm to 2.4 mm, and the tooth top dimension S4 of the second tooth portion 512 in the direction of spacing between the second linear grooves 62 is 1.5 mm to 2.4 mm. As a result, the second tooth portion 512 has a larger area, which facilitates achieving a tooth area ratio of 50% to 60%, and helps meet grip requirements to provide greater friction. Furthermore, the welding head 400 has a simple structure, is easy to process, and has low manufacturing costs.

[0188] In some embodiments of the present application, as shown in FIG15 , the welding end 401 is in an elongated strip shape, the length direction of the first linear groove 61 is parallel to the width direction of the welding end 401, the length direction of the second linear groove 62 is parallel to the length direction of the welding end 401, and the second linear groove 62 is located in the center of the width of the welding end 401. The tooth area of ​​the welding end 401 accounts for 60%-70%. For example, the tooth area ratio is 60%, 62%, 64%, 66%, 68%, 70%, etc.

[0189] For example, as shown in FIG15 , the length direction of the welding end 401 extends along the fourth direction E, and the width direction of the welding end 401 extends along the fifth direction F. The length direction of the first linear groove 61 is parallel to the fifth direction F, and the length direction of the second linear groove 62 is parallel to the fourth direction E. The second linear groove 62 is located at the center of the welding end 401 in the fifth direction F. Thus, the plurality of teeth 51 defined by the plurality of first linear grooves 61 and the second linear grooves 62 can present a double-row grid form.

[0190] As a result, the welding head 400 has a simple structure and is easy to manufacture. The length direction of the first linear groove 61 is parallel to the width direction of the welding end 401, and the length direction of the second linear groove 62 is parallel to the length direction of the welding end 401 and located in the center of the width of the welding end 401. This helps reduce the proportion of the tooth groove 6 and significantly increases the tooth area ratio of the welding end 401, reaching 60%-70%. This allows the contour of the laser weld to fall more deeply into the compacted area 3211, thereby further improving the problem of thermal cracking in the laser weld contour. This in turn improves the conductivity yield and connection strength between the tab portion 32 and the conductive portion 20, and enhances the reliability of the battery cell 102. Furthermore, due to the small number of second linear grooves 62, the area of ​​the tooth portion 51 defined between adjacent first and second linear grooves 61, 62 is larger, which helps increase the volume of the laser weld molten pool falling into the compacted area 3211, thereby reducing pores in the molten pool and improving the flow capacity of the laser weld.

[0191] Exemplarily, referring to Figure 15, the tooth portion 51 includes a third tooth portion 513 defined between the adjacent first straight groove 61 and the second straight groove 62, and the tooth top dimension S5 of the third tooth portion 513 in the spacing direction of the first straight groove 61 is 2mm-2.4mm, and the tooth top dimension S6 of the third tooth portion 513 in the length direction of the first straight groove 61 is 3.5mm-4.5mm.

[0192] Thus, the third tooth portion 513 is a long strip of tooth portion 51 extending in the longitudinal direction along the width direction of the welding end 401. The large area of ​​the third tooth portion 513 is conducive to achieving a tooth area ratio of 60%-70%, and is conducive to meeting the grip requirements to provide greater friction. Moreover, the welding head 400 has a simple structure, is easy to process, and has low manufacturing costs. When the laser weld is constructed as a long strip extending in the longitudinal direction of the ultrasonic weld mark (i.e., the longitudinal direction of the welding end 401), two rows of the above-mentioned long strip of third tooth portions 513 are provided on the welding end 401. This can reduce the volume of the laser weld falling in the fluffy area 3212 in the width direction of the ultrasonic weld mark, thereby reducing the pores in the molten pool and improving the flow capacity of the laser weld.

[0193] For example, as shown in FIG15 , the groove width W1 of the first linear groove 61 is smaller than the groove width W2 of the second linear groove 62. Thus, when the laser weld is configured as an elongated strip extending along the length of the ultrasonic weld mark (i.e., the length of the weld end 401), setting the groove width of the first linear groove 61 smaller than the groove width of the second linear groove 62 allows the first linear groove 61 to have a narrower puffy region 3212, thereby reducing the puffy region 3212 along the two long sides of the laser weld profile, thereby improving the risk of thermal cracking in the laser weld profile. For example, as shown in FIG15 , the groove width W1 of the first linear groove 61 is 0.2-0.4 mm, and the groove width W2 of the second linear groove 62 is 0.4-0.6 mm.

[0194] In some other embodiments of the present application, as shown in Figure 16, the welding end 401 is long and narrow, and the welding tooth 5 includes a fourth tooth portion 514 (the shaded area in Figure 16 is used to show the fourth tooth portion 514). The length direction of the fourth tooth portion 514 matches the length direction of the welding end 401, and the width direction of the fourth tooth portion 514 matches the width direction of the welding end 401. There are multiple fourth tooth portions 514 and they are spaced apart along the width direction of the welding end 401.

[0195] For example, as shown in FIG16 , the length direction of the welding end 401 extends along the fourth direction E, the width direction of the welding end 401 extends along the fifth direction F, the length direction of the fourth tooth portion 514 is parallel to the fourth direction E, and the width direction of the fourth tooth portion 514 is parallel to the fifth direction F. Therefore, by configuring the fourth tooth portion 514 as an elongated strip that matches the length direction of the welding end 401 and arranging a plurality of elongated fourth tooth portions 514 along the width direction of the welding end 401, the area of ​​each fourth tooth portion 514 is increased, thereby increasing the tooth area ratio of the welding end 401. This allows the contour of the laser weld to fall more within the compacted area 3211, thereby more broadly alleviating the problem of thermal cracking in the contour of the laser weld. This further improves the conductivity yield and connection strength between the tab portion 32 and the conductive portion 20, and enhances the reliability of the battery cell 102.

[0196] In addition, in conjunction with Figure 17, when the laser weld (the shaded area in Figure 17 is used to show the laser weld) is constructed as a long strip extending along the length direction of the ultrasonic weld mark (that is, the length direction of the welding end 401), by setting the fourth tooth portion 514 to a long strip matching the length direction of the welding end 401, and arranging a plurality of long strip-shaped fourth tooth portions 514 along the width direction of the welding end 401, the two long sides of the outline of the laser weld can correspond to the compacted area 3211 of the long strip corresponding to the fourth tooth portion 514, so that the two long sides of the outline of the laser weld can fall more into the compacted area 3211 corresponding to the fourth tooth portion 514, which is beneficial to improving the problem of thermal cracks in the outline of the laser weld.

[0197] In some embodiments of the present application, as shown in FIG16 and FIG17 , two fourth tooth portions 514 are spaced apart along the width direction of the welding end 401. The ratio of the tooth top length S7 of the fourth tooth portion 514 in the longitudinal direction of the welding end 401 to the length J1 of the welding end 401 is 75%-85%, the ratio of the tooth top width S8 of the fourth tooth portion 514 in the width direction of the welding end 401 to half the width J2 of the welding end 401 is 75%-85%, and the tooth area of ​​the welding end 401 accounts for 70%-80%. For example, the tooth area ratio is 70%, 72%, 74%, 76%, 78%, 80%, etc.

[0198] As a result, the area of ​​each fourth tooth portion 514 can be further increased, thereby increasing the tooth area ratio of the welding end 401 to 70%-80%. This allows the molten pool of the laser weld to fall more deeply into the compacted area 3211, thereby reducing pores within the molten pool and improving the flow capacity of the laser weld. In addition, when the laser weld is constructed as a long strip extending along the length of the ultrasonic weld mark, the two long sides of the laser weld profile can respectively fall into the compacted areas 3211 corresponding to the two fourth tooth portions 514, facilitating the configuration of the laser weld and improving the problem of thermal cracking in the laser weld profile.

[0199] In some embodiments of the present application, as shown in Figures 16 and 17, each long side of the fourth tooth portion 514 has a plurality of protrusions 5141 spaced apart along the length direction of the welding end 401, and the protrusions 5141 protrude toward the width direction of the welding end 401.

[0200] In the above technical solution, each long side of the fourth tooth portion 514 is uneven, which helps to improve the grip during welding, so that the fourth tooth portion 514 can effectively compact the pole piece 320, improve the compaction rate of the compaction area 3211 corresponding to the fourth tooth portion 514, and further improve the problem of thermal cracks in the contour of the laser weld.

[0201] In some embodiments of the present application, as shown in Figures 16 and 17, the welding tooth 5 also includes a plurality of fifth teeth 515 arranged between the two fourth teeth 514 and spaced apart along the length direction of the welding end 401. The convex portions 5141 on one side of the two fourth teeth 514 are positioned relative to each other, and two opposite convex portions 5141 are respectively arranged between each adjacent two fifth teeth 515, and the profile of the fourth tooth 514 matches the profile of the fifth tooth 515.

[0202] In the above technical solution, the welding end 401 can be further utilized to construct the welding tooth 5, thereby increasing the tooth area ratio of the welding end 401. When the two long sides of the laser weld correspond to the compacted areas 3211 corresponding to the two fourth tooth portions 514, the laser weld can also cover at least part of the compacted areas 3211 corresponding to the multiple fifth tooth portions 515, thereby facilitating increasing the portion of the laser weld that falls in the compacted area 3211, further improving the problem of pores appearing in the molten pool of the laser weld, and further improving the conductivity yield of the gathered portion 321 and the conductive portion 20. Moreover, since the contour of the fifth tooth portion 515 matches the contour of the two fourth tooth portions 514, that is, the protruding position of the contour of the fourth tooth portion 514 corresponds to the recessed position of the contour of the fifth tooth portion 515, it is beneficial to further fully utilize the spatial structure of the welding tooth 5 at the welding end 401, increase the area of ​​the fourth tooth portion 514 and the fifth tooth portion 515, further increase the tooth area ratio, further improve the problem of pores in the molten pool of the laser weld, and improve the conductivity yield of the converged portion 321 and the conductive portion 20.

[0203] As shown in FIG16 , the tooth groove 6 includes a first dividing groove 63 spaced between two fourth tooth portions 514 and between the fourth tooth portion 514 and the fifth tooth portion 515. For example, the tooth top width S9 of the fifth tooth portion 515 in the width direction of the welding end 401 is less than 1 / 3 of the tooth top width S8 of the fourth tooth portion 514 in the width direction of the welding end 401, and the groove width W3 of the first dividing groove 63 is less than 2 / 3 of the tooth top width S9 of the fifth tooth portion 515 in the width direction of the welding end 401. As a result, the spacing between the two fourth tooth portions 514 and the spacing between the fourth tooth portion 514 and the fifth tooth portion 515 are relatively small, so that the molten pool of the laser weld is mostly located in the compacted area 3211, which helps to alleviate the problem of porosity in the molten pool of the laser weld and further improves the conductivity yield of the converged portion 321 and the conductive portion 20.

[0204] In some embodiments of the present application, as shown in Figures 16 and 17, the welding tooth 5 includes a plurality of sixth tooth portions 516, which are multiple and spaced apart and arranged around the two fourth tooth portions 514, and the profile of the fourth tooth portion 514 matches the profile of the sixth tooth portion 516.

[0205] In the above technical solution, a plurality of sixth teeth 516 are arranged around the two fourth teeth 514, and since the contour of the sixth teeth 516 matches the contour of the fourth teeth 514, that is, the protruding position of the contour of the fourth teeth 514 corresponds to the recessed position of the contour of the sixth teeth 516, it helps to improve the grip during welding, so that the fourth teeth 514 can effectively compact the tab 320, improve the compaction rate of the compaction area 3211 corresponding to the fourth teeth 514, and further improve the problem of thermal cracks in the contour of the laser weld.

[0206] 16 , the tooth groove 6 includes a second dividing groove 64 separating the fourth tooth portion 514 and the sixth tooth portion 516 and separating two adjacent sixth tooth portions 516. For example, the groove width W4 of the second dividing groove 64 may be equal to or close to the groove width W3 of the first dividing groove 63.

[0207] In some embodiments, a dimension K1 of the protrusion 5141 along the length of the welding end 401 is 1.5 mm to 2.4 mm, and a dimension K2 of the protrusion 5141 along the width of the welding end 401 is 0.2 mm to 1.2 mm. In the above technical solution, by setting the dimensions of the protrusion 5141 as described above, the gripping force during welding is improved, so that the fourth tooth portion 514 can effectively compact the tab 320.

[0208] In some embodiments, with reference to FIG16 , the sixth tooth portion 516 includes first sub-teeth 5161 located on either side of the two fourth tooth portions 514 in the width direction of the welding end 401, and second sub-teeth 5162 located on either side of the two fourth tooth portions 514 in the length direction of the welding end 401. The first sub-teeth 5161 are multiple and spaced apart along the length direction of the welding end 401, and the second sub-teeth 5162 are multiple and spaced apart along the width direction of the welding end 401. The tooth top width S10 of the first sub-teeth 5161 in the length direction of the welding end 401 is 1.8 mm to 2.2 mm, and the tooth top width S11 of the second sub-teeth 5162 in the width direction of the welding end 401 is 0.8 mm to 1.2 mm. The above technical solution is beneficial for improving the grip during welding, allowing the fourth tooth portion 514 to effectively compact the tab 320.

[0209] In some embodiments, as shown in FIG12 , the groove width W0 of the tooth groove 6 is 0.2 mm to 0.6 mm, such as 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, etc. For example, the tooth groove 6 can be composed of a plurality of linear grooves. For example, the first linear groove 61, the second linear groove 62, the first dividing groove 63, and the second dividing groove 64 are all linear grooves, and the groove width of each linear groove can be in the range of 0.2 mm to 0.6 mm. Thus, the groove width of the tooth groove 6 is relatively small, thereby reducing the proportion of the tooth groove 6 on the welding end 401, thereby increasing the proportion of the welding tooth 5, and thus increasing the proportion of the compacted area 3211 on the converged portion 321.

[0210] In some embodiments, as shown in Figures 12 and 13, the tooth top dimension S0 of the tooth portion 51 in the normal direction of the adjacent tooth groove 6 is greater than or equal to 1.5 mm. The tooth portion 51 is separated by the tooth groove 6, and the dimension of the tooth top of the tooth portion 51 in the normal direction of the tooth groove 6 that defines the tooth portion 51 is the tooth top dimension S0. Exemplarily, there are multiple tooth portions 51, such as the first tooth portion 511, the second tooth portion 512, the third tooth portion 513, the fourth tooth portion 514, the fifth tooth portion 515, and the sixth tooth portion 516. The tooth top dimension S0 of any tooth portion 51 in the normal direction of the adjacent tooth groove 6 can be greater than or equal to 1.5 mm. As a result, the area of ​​a single tooth portion 51 is not too small, which is conducive to improving the compaction rate of the compaction area 3211.

[0211] In some embodiments, as shown in FIG12 , the tooth height H of the tooth portion 51 is less than or equal to 2.5 mm, and the projection distance E between the tooth top and the tooth bottom of the tooth portion 51 is 0.1 mm-0.2 mm.

[0212] It is understood that the tooth height H refers to the height at the outer end surface perpendicular to the welding end 401 (the surface where the top surface of each tooth portion 51 is located), and the projection distance E between the tooth top and the tooth bottom refers to the distance between the projections of the top surface of each tooth portion 51 on the surface where the top surface of each tooth portion 51 is located on the outer end surface of the welding end 401. For example, there are multiple tooth portions 51, such as the first tooth portion 511, the second tooth portion 512, the third tooth portion 513, the fourth tooth portion 514, the fifth tooth portion 515, and the sixth tooth portion 516 described above. The tooth height H of any tooth portion 51 is less than or equal to 2.5 mm, and the projection distance E between the tooth top and the tooth bottom of any tooth portion 51 can be 0.1 mm to 0.2 mm.

[0213] Therefore, by setting the tooth height H of the tooth portion 51 to be less than or equal to 2.5 mm and the projected spacing E between the tooth top and the tooth bottom of the tooth portion 51 to be 0.1 mm-0.2 mm, the side surface of the tooth portion 51 has a certain inclination, which is convenient for improving the compaction rate and reducing the sharpness of the edge of the tooth portion 51 to improve the problem of scratching the pole piece 320.

[0214] In some embodiments, as shown in FIG12 , the edge of the welding end 401 is rounded, and the rounded radius R is 0.5 mm to 2 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 2 mm, etc. This can alleviate the problem of the edge of the welding end 401 scratching the edge of the tab 320 during ultrasonic welding, facilitate smooth welding, and improve the connection reliability and conductivity between the tab portion 32 and the conductive portion 20. Furthermore, a larger rounded radius R facilitates effective welding under high welding parameters without damaging the foil, thereby improving the problem of cracking of the tab 320.

[0215] In related technologies, ultrasonic welding heads usually use uniform welding teeth, and the tooth area of ​​the welding end accounts for less than 40%. After the pole ear is welded with the ultrasonic welding head, the compacted area and the fluffy area in the obtained ultrasonic weld mark are basically evenly distributed, and the area of ​​the compacted area accounts for less than 40%, and the compaction rate of the compacted area is less than 5%. When the ultrasonic weld mark is welded together with the pole column component by laser welding, most of the contour of the laser weld will fall in the fluffy area. Since the multiple layers of pole ear sheets in the fluffy area are not fused together, there are gaps between the layers. These gaps will cause thermal cracks in the contour of the laser weld, affecting the connection reliability and conductivity yield between the pole ear and the conductive part, reducing the overcurrent capacity of the battery cell, and affecting the reliability of the battery cell.

[0216] In the embodiment of the present application, by improving the distribution, shape, size, etc. of the welding teeth 5 of the welding end 401 of the welding head 400, the processed ultrasonic weld mark can provide a larger compaction area 3211 and improve the compaction rate of the compaction area 3211, and can provide a tight compaction area 3211 along the direction of laser welding between the pole ear portion 32 and the conductive portion 20 (for example, along the length direction of the welding end 401), thereby effectively improving the problem of thermal cracks in the contour of the laser weld, improving the connection reliability and conductivity yield between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0217] In addition, the welding parameters, tooth arrangement, etc. can be adjusted accordingly according to different welding methods. For example, when welding using the welding head 400 of the embodiment of the present application, it can be vibrated along the length direction of the welding end 401, or it can be vibrated along the width direction of the welding end 402. For example, the entire welding head 400 can be enlarged or reduced by 20%-60% depending on the vibration direction. Therefore, the welding head 400 of the embodiment of the present application has a wide range of applications.

[0218] 18 and 19 , an embodiment of the present application further proposes an ultrasonic welding device 2000, comprising: a welding head 400, a welding seat 500 and a driving cylinder 600, wherein the driving cylinder 600 is arranged on a side of the welding head 400 away from the welding seat 500, and the driving cylinder 600 is used to drive the welding head 400 to move toward the welding seat 500, and the welding head 400 is the welding head 400 of any of the above-mentioned schemes.

[0219] For example, the drive cylinder 600 is located directly above the ultrasonic welding device 2000. The drive cylinder 600 is connected to the welding head 400 via guide rails, a conversion block, and the like. The drive cylinder 600, welding head 400, and welding base 500 are arranged in a straight line from top to bottom, making the ultrasonic welding process more stable, reducing mechanical losses, and causing negligible deformation of the welding head 400. During welding, the multi-layered tab 320 to be welded can be placed between the welding head 400 and the welding base 500. The drive cylinder 600 is activated, pushing the welding head 400 downward toward the welding base 500. The welding head 400 and the welding base 500 weld the multi-layered tab 320 together, forming an ultrasonic weld mark.

[0220] Since the welding head 400 according to the embodiment of the present application is conducive to increasing the area of ​​the compacted region 3211 in the ultrasonic weld mark, the ultrasonic weld mark welded by the ultrasonic welding device 2000 has a larger compacted region 3211, which is conducive to improving the subsequent laser welding effect of the pole ear portion 32 and the conductive portion 20.

[0221] In the embodiments of the present application, the type of the driving cylinder 600 is not limited, and can be, for example, an electric cylinder, a hydraulic cylinder, or a pneumatic cylinder. By increasing the pressure of the driving cylinder 600, the compaction rate of the compaction area 3211 can be increased. For example, in some embodiments, the driving cylinder 600 is a pneumatic cylinder, and the diameter of the cylinder is greater than 125 mm.

[0222] In the embodiment of the present application, the thickness T1 of the compacted region 3211 is less than the theoretical thickness T2 of the tab portion 32, resulting in a compaction rate greater than 0%, indicating that the tab 320 in the compacted region 3211 needs to be compressed and yielded and undergo plastic deformation. Therefore, according to the ultrasonic welding device 2000 of the embodiment of the present application, the surface pressure provided by the welding head 400 must be greater than the yield strength of the tab 320, such as the aluminum foil.

[0223] For example, under ultrasonic conditions, the yield strength of the tab 320, such as aluminum foil, is Rp 0.2 = σ, the length of the welding end 401 of the welding head 400 is J1, the width of the welding end 401 is J2, and the area of ​​the welding end 401 of the welding head 400 is S = J1 × J2. When the driving cylinder 600 is a cylinder, the pressure provided by the cylinder is P, the diameter of the cylinder is d, and the surface pressure provided by the welding head 400 is Pπ(d / 2) 2 / S, where Pπ(d / 2) 2 When / S≥σ, the tab 320 may be compressed and yielded and undergo plastic deformation, so that the compaction rate of the compacted area 3211 may be greater than 0%.

[0224] As can be seen from the above formula, the compaction rate of the compaction area 3211 can be increased by increasing the diameter d of the cylinder. For example, when the driving cylinder 600 is a pneumatic cylinder, after selecting the welding head 400, the area S of the welding end 401 is fixed, and the air supply pressure of the cylinder in the ultrasonic welding device 2000 can be adjusted to the maximum, such as the upper limit of the air supply pressure in a factory building is generally 0.6 MPa. Subsequently, after welding with a pneumatic cylinder with a diameter of typically 100 mm or 125 mm, the surface pressure provided by the welding head 400 is still less than the yield strength of the tab 320, such as the aluminum foil.

[0225] By increasing the diameter of the cylinder so that the diameter of the cylinder is greater than 125 mm, the surface pressure provided by the welding head 400 can be increased, the interlayer gap of the pole piece 320 can be realized, and the compaction rate of the compaction area 3211 can be increased, creating favorable conditions for subsequent laser welding and improving the problem of thermal cracks in the contour of the laser weld.

[0226] The ultrasonic welding machine in the related technology cannot form an effective interlayer weld after ultrasonic welding of the pole ear. There is an interlayer gap between the multi-layer pole ear sheets, and the interlayer gap is large, and the compaction rate is low. During the cooling stage after laser welding the ultrasonic weld mark and the conductive part, the outline of the laser weld forms a thermal crack problem, affecting the performance of the battery cell.

[0227] The ultrasonic welding device 2000 of this embodiment can be a direct pressure welder with stronger welding capability. By increasing the diameter of the cylinder, an ultra-high pressure can be provided to the pole tab 320 during the ultrasonic pre-welding process. Under this pressure, the friction heat generated by the ultrasonic pre-welding can more easily soften the aluminum foil, thereby forming a tighter interlayer bond, which can form an effective interlayer welding of the pole tab 320. The pole tab undergoes obvious plastic deformation, achieving a solid welding effect between the multi-layer pole tab 320, reducing the interlayer gap, and improving the compaction rate of the compacted area 3211. When laser welding the ultrasonic weld mark and the conductive part 20, the contour of the formed laser weld is not prone to thermal cracks, thereby improving the problem of thermal cracks in the contour of the laser weld, improving the conductive yield and connection strength of the pole tab 32 and the conductive part 20, and reducing the pores in the molten pool of the laser weld, improving the current flow capacity of the laser weld, and improving the reliability of the battery cell 102.

[0228] The ultrasonic welding device 2000 of the present embodiment utilizes an ultra-large diameter cylinder and optimizes the welding teeth 5 of the welding head 400, allowing the tabs 320 to undergo plastic deformation under extremely high pressure, thereby reducing the interlayer gaps between the tabs 320. Furthermore, the optimized welding teeth 5 provide a larger compaction area, which helps increase the area of ​​the compacted region 3211 in the ultrasonic weld mark. This provides a good foundation for the subsequent laser welding of the tab portion 32 and the conductive portion 20, thereby improving the problem of thermal cracking in the laser weld profile. This optimization method is simple and highly reliable, and is an effective and reliable method for improving thermal cracking in laser welding after ultrasonic pre-welding, without the need to adopt other process designs or add mechanical components to solve this technical problem.

[0229] For example, the cylinder has a diameter of 160 mm or 200 mm. This makes the cylinder easier to machine and more functional, and the compaction rate of the compacted area 3211 is higher, effectively improving the problem of thermal cracks in the laser weld profile, improving the conductivity yield and connection strength between the tab 32 and the conductive portion 20, and reducing porosity in the laser weld molten pool, thereby improving the current flow capacity of the laser weld and enhancing the reliability of the battery cell 102.

[0230] 2-7 , an embodiment of the present application further provides a battery cell 102, comprising: a shell component 1, a pole component 2, and an electrode assembly 3, wherein the pole component 2 is provided in the shell component 1, the pole component 2 includes a conductive portion 20, the electrode assembly 3 is accommodated in the shell component 1 and includes a pole lug portion 32, the pole lug portion 32 includes a plurality of pole lug sheets 320 arranged in a stacked manner, the plurality of pole lug sheets 320 are connected to form a gathered portion 321, the gathered portion 321 is processed by an ultrasonic welding device 2000 of any of the above-mentioned schemes, and a compacted area 3211 is processed by welding teeth 5, the gathered portion 321 overlaps with the conductive portion 20 and is connected to form a connecting portion 4, the gathered portion 321 includes a compacted area 3211, the thickness of the compacted area 3211 is less than the stacked thickness of the plurality of pole lug sheets 320 in the pole lug portion 32, and the connecting portion 4 includes a first portion 41 formed in the gathered portion 321, at least most of the contour line of the first portion 41 is located in the compacted area 3211.

[0231] In the above technical solution, since at least part of the contour line of the portion of the connecting portion 4 formed on the gathered portion 321 is set within the compacted area 3211, the multi-layer pole tab sheets 320 in the compacted area 3211 are very tightly combined together, which is beneficial to improving the problem of thermal cracks in the contour of the connecting portion 4, improving the conductive yield and connection strength between the pole tab portion 32 and the conductive portion 20, and enhancing the current flow capacity and reliability of the battery cell 102.

[0232] In some embodiments, at least a majority of the contour of the first portion 41 lies within the compacted region 3211. This means that at least a majority of the contour of the portion of the connection portion 4 formed on the gathered portion 321 lies within the compacted region 3211. This means that at least 50% (including 50%) of the contour of the portion of the connection portion 4 formed on the gathered portion 321 lies within the compacted region 3211. Alternatively, the proportion of the contour of the first portion 41 that falls within the compacted region 3211 is greater than the proportion that falls within the fluffy region 3212. This can significantly improve the risk of thermal cracking in the laser weld profile, further enhance the conductivity yield and connection strength between the tab portion 32 and the conductive portion 20, and improve the reliability of the battery cell 102.

[0233] In some embodiments, in combination with Figures 7 and 17, the connecting portion 4 extends from the outer surface of the gathering portion 321 toward the conductive portion 20, and the first portion 41 includes a surface portion 411 formed on the outer surface of the gathering portion 321, and more than 60% of the contour line 4x of the surface portion 411 falls in the compacted area 3211.

[0234] In the above technical solution, by setting the extension direction of the connecting portion 4 to be from the gathering portion 321 to the conductive portion 20, it is convenient for the welding head 400 to align with the gathering portion 321, so that the welding head 400 can reasonably design the welding trajectory according to the distribution of the compacted area 3211 and the fluffy area 3212 on the gathering portion 321, and accurately weld along the welding trajectory, so that at least most of the contour line of the part of the connecting portion 4 formed on the gathering portion 321 can be reliably located in the compacted area 3211, thereby effectively improving the conductive yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the current carrying capacity and reliability of the battery cell 102.

[0235] Furthermore, by ensuring that at least 60% of the contour line 4x of the surface portion 411 falls within the compacted region 3211, the problem of thermal cracking in the weld profile of the connecting portion 4 that falls on the surface of the gathered portion 321 can be further alleviated. Furthermore, since the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, the contour line 4y of the inner portion 412 can extend from the contour line 4x of the surface portion 411 toward the conductive portion 20. When at least 60% of the contour line 4x of the surface portion 411 falls within the compacted region 3211, this helps further increase the proportion of the contour line 4y of the inner portion 412 that falls within the compacted region 3211 relative to that falling within the fluffy region 3212, thereby further improving the overall problem of thermal cracking in the contour line of the first portion 41 of the connecting portion 4 formed in the gathered portion 321.

[0236] In some embodiments, the compaction rate of the compaction area 3211 is greater than or equal to 12%. Thus, by setting the compaction rate of the compaction area 3211 to be greater than or equal to 12%, there is almost no gap in the compaction area 3211, and the portion of the connecting part 4 that falls into the compaction area 3211 is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connecting part 4, as well as the reliability and conductivity yield of the connecting part 4 connecting the conductive part 20 and the gathered part 321.

[0237] For example, the thickness T1 of the compacted area after welding of a large-toothed welding head can be tested with a micrometer or a ten-thousand-meter, while the thickness T1 of the compacted area after welding of a small-toothed welding head can be tested by cutting a cross section using an optical microscope using a crystal glue sample or other method.

[0238] The following seven groups of experiments were conducted for comparison. In each experimental sample, 50 layers of tab sheets were stacked in the tab portion, the thickness of a single tab sheet was 13 μm, and the theoretical thickness T2 of the tab portion was 650 μm.

[0239] In Experiment 1, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 1 were obtained. Figure 20 shows the local cross-sectional morphology of the gathered part of Comparative Example 1. It can be seen that the thickness T1 of the compacted area is 765 μm, and the calculated compaction rate is -17.7%. Figure 21 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 100%.

[0240] In Experiment 2, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 2 were obtained. Figure 22 shows the local cross-sectional morphology of the gathered part of Comparative Example 2. It can be seen that the thickness T1 of the compacted area is 711 μm, and the calculated compaction rate is -9.4%. Figure 23 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 70%.

[0241] In Experiment 3, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 3 were obtained. Figure 24 shows the local cross-sectional morphology of the gathered part of Comparative Example 3. It can be seen that the thickness T1 of the compacted area is 664 μm, and the calculated compaction rate is -2.2%. Figure 25 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 40%.

[0242] In Experiment 4, the ultrasonic pre-welding effect and laser welding effect of Example 1 were obtained. Figure 26 shows the local cross-sectional morphology of the gathered part of Example 1. It can be seen that the thickness T1 of the compacted area is 609 μm, and the calculated compaction rate is 6.3%. Figure 27 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that a small amount of thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 15%.

[0243] In Experiment 5, the ultrasonic pre-welding effect and laser welding effect of Example 2 were obtained. Figure 28 shows the local cross-sectional morphology of the gathered part of Example 2. It can be seen that the thickness T1 of the compacted area is 564 μm, and the calculated compaction rate is 13.2%. Figure 29 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that there is almost no thermal crack in the outline of the laser weld.

[0244] In Experiment 6, the ultrasonic pre-welding effect and laser welding effect of Example 3 were obtained. Figure 30 shows the local cross-sectional morphology of the gathered part of Example 3. It can be seen that the thickness T1 of the compacted area is 522 μm, and the calculated compaction rate is 19.7%. Figure 31 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that there is no thermal crack in the outline of the laser weld.

[0245] In experiment seven, the ultrasonic pre-welding effect and laser welding effect of embodiment four were obtained. FIG32 shows the local cross-sectional morphology of the gathered portion of embodiment four. It can be seen that the thickness T1 of the compacted area is 362 μm, and the calculated compaction rate is 44.3%. FIG33 shows the local cross-sectional morphology of the gathered portion and the conductive portion after laser welding. It can be seen from the figure that there is no thermal crack in the outline of the laser weld.

[0246] Through the above experimental comparison, it can be found that when the compaction rate exceeds 6%, the problem of thermal cracks in the contour of the laser weld can be significantly improved. When the compaction rate exceeds 12%, the contour of the laser weld can basically be free of thermal cracks.

[0247] This application also provides a battery 100, comprising a battery cell 102 according to any of the above-described solutions. Because the reliability of the battery cell 102 according to the embodiments of this application is improved, this helps improve the reliability of the battery 100. It is worth noting that the battery 100 according to the embodiments of this application may or may not include a housing 101.

[0248] Exemplarily, the battery 100 further includes a busbar component, and there are multiple battery cells 102, and at least two of them are electrically connected through the busbar component. In this way, multiple battery cells 102 can be connected in series and / or in parallel. For example, when multiple battery cells 102 are connected in series, the anode of one battery cell 102 is connected to the cathode of the next battery cell 102 through a busbar component, and at the same time, the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 through another busbar component. For example, the busbar component can be directly or indirectly electrically connected to the pole body 21 in the pole component 2 to achieve electrical connection between the battery cell 102 and the busbar component.

[0249] The present application also provides an electrical device comprising the battery 100 of any of the aforementioned solutions. The battery 100 is configured to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems employing the battery 100. The improved reliability of the battery 100 improves the operating performance of the electrical device.

[0250] 13 , a welding head 400 according to a specific embodiment of the present application will be described below.

[0251] The welding end 401 of the welding head 400 is divided into welding teeth 5 by a first straight groove 61 and a second straight groove 62. The first straight grooves 61 are multiple and arranged in parallel, and the second straight grooves 62 are multiple and arranged in parallel. The welding end 401 is long and narrow. The length direction of the first straight groove 61 intersects the length direction of the welding end 401 at 45°. The length direction of the second straight groove 62 is symmetrical with the length direction of the first straight groove 61 about the width direction of the welding end 401. Multiple first straight grooves 61 and multiple second straight grooves 62 are cross-arranged to define multiple diamond-shaped first tooth portions 511. The welding end 401 as a whole presents a diamond grid shape.

[0252] The tooth tip dimension S1 of the first tooth portion 511 in the direction of spacing between adjacent first linear grooves 61 is 1.6 mm to 2 mm, and the tooth tip dimension S2 of the first tooth portion 511 in the direction of spacing between adjacent second linear grooves 62 is 1.6 mm to 2 mm. The groove width W1 of the first linear groove 61 is 0.2 mm to 0.3 mm, and the groove width W2 of the second linear groove 62 is 0.2 mm to 0.3 mm. The tooth height of the first tooth portion 511 is 0.2 mm, and the projected distance between the tooth tip and tooth bottom of the first tooth portion 511 is 0.1 mm to 0.2 mm. The edge of the welding end 401 is rounded with a rounding radius of 1 mm. The welding end 401 is 24 mm long and 14 mm wide, and the tooth area of ​​the welding end 401 accounts for 40% to 50%.

[0253] The morphology and cross-section of the ultrasonic weld mark processed by the welding head 400 are shown in Figures 34 and 35. The area of ​​the compacted area 3211 relative to the welding end 401 accounts for 40%-50%, the compaction rate of the compacted area 3211 can reach 15%-20%, and there is almost no interlayer gap in the compacted area 3211.

[0254] 14 , a welding head 400 according to a specific embodiment of the present application will be described below.

[0255] The welding end 401 of the welding head 400 is divided into welding teeth 5 by a first straight groove 61 and a second straight groove 62. The first straight groove 61 is multiple and arranged in parallel, and the second straight groove 62 is multiple and arranged in parallel. The welding end 401 is long and narrow. The length direction of the first straight groove 61 is parallel to the width direction of the welding end 401, and the length direction of the second straight groove 62 is parallel to the length direction of the welding end 401. Multiple first straight grooves 61 and multiple second straight grooves 62 are cross-arranged to define multiple rectangular second tooth portions 512. The welding end 401 as a whole presents a grid shape.

[0256] The tooth tip dimension S3 of the second tooth portion 512 in the direction of spacing between the first linear grooves 61 is 1.5 mm to 2.4 mm, and the tooth tip dimension S4 of the second tooth portion 512 in the direction of spacing between the second linear grooves 62 is 1.5 mm to 2.4 mm. The groove width W1 of the first linear groove 61 is 0.2 mm to 0.4 mm, and the groove width W2 of the second linear groove 62 is 0.2 mm to 0.4 mm. The tooth height of the second tooth portion 512 is 0.2 mm, and the projected distance between the tooth tip and tooth bottom of the second tooth portion 512 is 0.1 mm to 0.2 mm. The edge of the welding end 401 is rounded with a rounding radius of 1 mm. The welding end 401 is 24 mm long and 14 mm wide, and the tooth area of ​​the welding end 401 accounts for 50% to 60%.

[0257] The morphology and cross-section of the ultrasonic weld mark produced by the welding head 400 are shown in FIG36-FIG37 . The area of ​​the compacted region 3211 accounts for 50%-60% of the area of ​​the welding end 401 , and there is almost no interlayer gap in the compacted region 3211 .

[0258] 15 , a welding head 400 according to a specific embodiment of the present application will be described below.

[0259] The welding end 401 of the welding head 400 is divided into welding teeth 5 by a first straight groove 61 and a second straight groove 62. The welding end 401 is in the shape of an elongated strip. There are multiple first straight grooves 61 and they are arranged in parallel. The length direction of the first straight groove 61 is parallel to the width direction of the welding end 401. The length direction of the second straight groove 62 is parallel to the length direction of the welding end 401 and the second straight groove 62 is located in the center of the width of the welding end 401. The second straight groove 62 is cross-arranged with the multiple first straight grooves 61 to define multiple elongated third tooth portions 513. The welding end 401 as a whole presents a double-row long strip grid shape.

[0260] The tooth top dimension S5 of the third tooth portion 513 in the spacing direction of the first straight groove 61 is 2mm-2.4mm, the tooth top dimension S6 of the third tooth portion 513 in the length direction of the first straight groove 61 is 3.5mm-4.5mm, the groove width W1 of the first straight groove 61 is 0.2mm-0.4mm, the groove width W2 of the second straight groove 62 is 0.4mm-0.6mm, the tooth height of the third tooth portion 513 is 0.2mm, the projected spacing between the tooth top and the tooth bottom of the third tooth portion 513 is 0.1mm-0.2mm, the edge of the welding end 401 is rounded and the rounding radius is 1.5mm, the length of the welding end 401 is 25mm, the width is 13.5mm, and the tooth area of ​​the welding end 401 accounts for 60%-70%.

[0261] The morphology and cross-section of the ultrasonic weld mark produced by the welding head 400 are shown in FIG38-FIG39 . The area of ​​the compacted region 3211 accounts for 60%-70% of the area of ​​the welding end 401 , and there is almost no interlayer gap in the compacted region.

[0262] 16 , a welding head 400 according to a specific embodiment of the present application will be described.

[0263] The welding end 401 of the welding head 400 divides the welding tooth 5 into two fourth tooth portions 514, multiple fifth tooth portions 515, and multiple sixth tooth portions 516 through the tooth groove 6. The profile of the fourth tooth portion 514 matches the profile of the fifth tooth portion 515, and the profile of the fourth tooth portion 514 matches the profile of the sixth tooth portion 516. The welding end 401 is in the shape of an elongated strip. The length direction of the fourth tooth portion 514 matches the length direction of the welding end 401. The width direction of the fourth tooth portion 514 matches the width direction of the welding end 401. The two fourth tooth portions 514 are spaced apart along the width direction of the welding end 401. Each long side of the fourth tooth portion 514 has a plurality of protrusions 5141 spaced apart along the length direction of the welding end 401. The protrusions 5141 protrude toward the width direction of the welding end 401. A plurality of fifth tooth portions 515 are disposed between the two fourth tooth portions 514, and the plurality of fifth tooth portions 515 are spaced apart along the length direction of the welding end 401. The protrusions 5141 on one side of the two fourth tooth portions 514 are positioned relative to each other, so that two opposing protrusions 5141 are respectively disposed between each adjacent two fifth tooth portions 515. A plurality of sixth tooth portions 516 are spaced apart and disposed around the two fourth tooth portions 514.

[0264] The sixth tooth portion 516 includes a first sub-tooth 5161 located on both sides of the two fourth tooth portions 514 in the width direction of the welding end 401, and a second sub-tooth 5162 located on both sides of the two fourth tooth portions 514 in the length direction of the welding end 401. There are multiple first sub-teeth 5161 and they are spaced apart along the length direction of the welding end 401. There are multiple second sub-teeth 5162 and they are spaced apart along the width direction of the welding end 401. The tooth top width S10 of the first sub-tooth 5161 in the length direction of the welding end 401 is 1.8mm-2.2mm, and the tooth top width S11 of the second sub-tooth 5162 in the width direction of the welding end 401 is 0.8mm-1.2mm.

[0265] The ratio of the tooth tip length S7 of the fourth tooth portion 514 in the longitudinal direction of the welding end 401 to the length J1 of the welding end 401 is 75%-85%. The ratio of the tooth tip width S8 of the fourth tooth portion 514 in the width direction of the welding end 401 to half the width J2 of the welding end 401 is 75%-85%. The groove width of each tooth groove 6 is 0.2mm-0.4mm. The tooth height of the fourth tooth portion 514 is 0.25mm. The projected distance between the tooth tip and tooth bottom of the fourth tooth portion 514 is 0.1mm-0.2mm. The edge of the welding end 401 is rounded with a rounding radius of 1.5mm. The welding end 401 is 25mm long and 14mm wide, and the tooth area of ​​the welding end 401 accounts for 70%-80%.

[0266] The morphology and cross-section of the ultrasonic weld mark produced by the welding head 400 are shown in FIG40-FIG41 . The area of ​​the compacted region 3211 accounts for 70%-80% of the area of ​​the welding end 401 , and there is almost no interlayer gap in the compacted region 3211 .

[0267] In this embodiment, a large-diameter cylinder is used in conjunction with a welding head having two large long strip teeth, which can effectively increase the area ratio of the compacted area 3211 relative to the welding end 401, and multiple small teeth are provided between and around the two large long strip teeth to provide welding grip, so that the foil can be firmly grasped during welding, which can provide greater friction.

[0268] In addition, the embodiments of this application are also applicable to batteries for 3C products, such as small batteries used in mobile phones and other devices. Batteries for 3C products have fewer tab layers and narrower tab widths. A flat welding head with spark erosion can be used for roughening, or a welding head with low weld teeth (e.g., tooth height ≤ 0.1mm) can be used. For example, power batteries typically have 30-120 tab layers, with a thickness of 13μm-15μm and a tooth height of 0.1mm-0.4mm. Batteries for 3C products typically have 10-50 tab layers, with a thickness of 6μm-10μm. The width of the ultrasonic weld mark is approximately 5mm, and the tooth height can be less than 0.1mm. Laser welding can use a high-frequency pulsed laser or a low-power continuous laser, and 60% to 100% of the laser weld contour should fall within the compacted area to improve battery reliability.

[0269] During the production of battery cells, ultrasonic welding can be used to pre-weld multiple tabs in the tab portion to form an ultrasonic weld mark, and then laser welding can be used to weld the ultrasonic weld mark to the conductive portion of the pole column component to achieve connection and electrical conduction between the electrode assembly and the pole column component. However, in the ultrasonic welding machine used for ultrasonic welding in the related art, after pre-welding the tab portion, the ultrasonic weld mark cannot form an effective interlayer weld. There are interlayer gaps between the multiple layers of tab sheets. The presence of these gaps will increase the porosity in the molten pool of the laser weld, reducing the flow capacity of the battery cell. In addition, during the cooling stage after laser welding, the contour of the laser weld will form thermal cracks, which will affect the connection reliability and conductivity yield between the tab portion and the conductive portion, and thus affect the performance of the battery cell.

[0270] The ultrasonic welding device provided in the embodiment of the present application can increase the cylinder diameter, increase the welding pressure, increase the compaction rate after ultrasonic pre-welding, reduce the gap between the tab layers, and then match the welding tooth design of the welding head to increase the area of ​​the compaction area and optimize the distribution of the compaction area, thereby helping to improve the problem of thermal crack deterioration caused by the contour of the laser weld, and reduce the proportion of pores in the laser weld molten pool, thereby improving the connection reliability and conductivity yield between the tab part and the conductive part, and improving the current flow capacity of the battery cell and improving the performance of the battery cell.

[0271] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0272] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A welding head, wherein: The welding end of the welding head has welding teeth and tooth grooves, the welding teeth are divided into a plurality of tooth portions arranged at intervals by the tooth grooves, and the tooth area of ​​the welding end accounts for greater than or equal to 40%.

2. The welding head according to claim 1, wherein: The tooth groove includes a first straight groove and a second straight groove arranged crosswise, the first straight grooves are multiple and arranged in parallel, the tooth portion is defined between adjacent first straight grooves and second straight grooves, and the groove width of the first straight groove and the groove width of the second straight groove are both smaller than the spacing between adjacent first straight grooves.

3. The welding head according to claim 2, wherein: The spacing between adjacent first straight grooves is 1.5 mm to 2.5 mm.

4. The welding head according to claim 2, wherein: There are multiple second linear grooves arranged in parallel, and the teeth are defined between adjacent first linear grooves and adjacent second linear grooves. The groove width of the first linear groove and the groove width of the second linear groove are both smaller than the spacing between adjacent second linear grooves.

5. The welding head according to claim 4, wherein: The distance between adjacent second straight grooves is 1.5 mm to 2.5 mm. The welding head according to claim 4 , wherein: The welding end is in the shape of a long strip, the length direction of the first straight groove intersects the length direction of the welding end at an acute angle, the length direction of the second straight groove is symmetrical to the length direction of the first straight groove about the width direction of the welding end, and the tooth area accounts for 40%-50%.

7. The welding head according to claim 6, wherein: The length direction of the first straight line groove intersects with the length direction of the welding end at 45°, and the tooth portion includes a first tooth portion defined between adjacent first straight line grooves and adjacent second straight line grooves, and the tooth top size of the first tooth portion in the direction of spacing between adjacent first straight line grooves is 1.6mm-2mm, and the tooth top size of the first tooth portion in the direction of spacing between adjacent second straight line grooves is 1.6mm-2mm.

8. The welding head according to claim 4, wherein: The welding end is in the shape of an elongated strip, the length direction of the first linear groove is parallel to the width direction of the welding end, the length direction of the second linear groove is parallel to the length direction of the welding end, and the tooth area accounts for 50%-60%.

9. The welding head according to claim 8, wherein: The tooth portion includes a second tooth portion defined between adjacent first straight grooves and adjacent second straight grooves, the tooth top size of the second tooth portion in the direction of spacing between the first straight grooves is 1.5mm-2.4mm, and the tooth top size of the second tooth portion in the direction of spacing between the second straight grooves is 1.5mm-2.4mm.

10. The welding head according to claim 2, wherein: The welding end is in the shape of an elongated strip, the length direction of the first straight groove is parallel to the width direction of the welding end, the length direction of the second straight groove is parallel to the length direction of the welding end and is located in the center of the width of the welding end, and the tooth area accounts for 60%-70%.

11. The welding head according to claim 10, wherein: The tooth portion includes a third tooth portion defined between the adjacent first straight groove and the second straight groove, the tooth top size of the third tooth portion in the spacing direction of the first straight groove is 2mm-2.4mm, and the tooth top size of the third tooth portion in the length direction of the first straight groove is 3.5mm-4.5mm.

12. The welding head according to claim 10, wherein: The groove width of the first straight groove is smaller than the groove width of the second straight groove.

13. The welding head according to claim 1, wherein: The welding end is in the shape of an elongated strip, and the welding tooth includes a fourth tooth portion, the length direction of the fourth tooth portion matches the length direction of the welding end, and the width direction of the fourth tooth portion matches the width direction of the welding end. There are multiple fourth tooth portions and they are spaced apart along the width direction of the welding end.

14. The welding head according to claim 13, wherein: The fourth tooth portions are two spaced apart along the width direction of the welding end, and the ratio of the tooth top length of the fourth tooth portion in the length direction of the welding end to the length of the welding end is 75%-85%, the ratio of the tooth top width of the fourth tooth portion in the width direction of the welding end to half of the width of the welding end is 75%-85%, and the tooth area accounts for 70%-80%.

15. The welding head according to claim 14, wherein: Each long side of the fourth tooth portion has a plurality of protrusions arranged at intervals along the length direction of the welding end, and the protrusions protrude toward the width direction of the welding end.

16. The welding head according to claim 15, wherein: The welding tooth also includes a plurality of fifth teeth portions arranged between the two fourth teeth portions and spaced apart along the length direction of the welding end. The convex portions on one side of the two fourth teeth portions are positioned opposite to each other, and two opposing convex portions are respectively arranged between each adjacent two fifth teeth portions. The contour line of the fourth tooth portion matches the contour line of the fifth tooth portion.

17. The welding head according to claim 15, wherein: The welding tooth includes a plurality of sixth tooth portions, which are arranged in a plurality and spaced apart around the two fourth tooth portions. The contour lines of the fourth tooth portions match the contour lines of the sixth tooth portions.

18. The welding head according to claim 15, wherein: The dimension of the protrusion along the length direction of the welding end is 1.5 mm to 2.4 mm, and the dimension of the protrusion along the width direction of the welding end is 0.2 mm to 1.2 mm.

19. The welding head according to any one of claims 1 to 18, wherein: The groove width of the tooth groove is 0.2mm-0.6mm.

20. The welding head according to any one of claims 1 to 19, wherein: A tooth tip dimension of the tooth portion in a normal direction of the adjacent tooth groove is greater than or equal to 1.5 mm.

21. The welding head according to any one of claims 1 to 20, wherein: The tooth height of the tooth portion is less than or equal to 2.5 mm, and the projection distance between the tooth top and the tooth bottom of the tooth portion is 0.1 mm-0.2 mm.

22. The welding head according to any one of claims 1 to 21, wherein: The edges of the welding ends are rounded, and the rounding radius is 0.5mm-2mm.

23. An ultrasonic welding device, wherein: include: A driving cylinder, a welding seat, and a welding head according to any one of claims 1 to 22, wherein the driving cylinder is arranged on a side of the welding head away from the welding seat, and is used to drive the welding head to move toward the welding seat.

24. The ultrasonic welding device according to claim 23, wherein: The driving cylinder is an air cylinder, and the diameter of the air cylinder is greater than 125 mm.

25. The ultrasonic welding device according to claim 24, wherein: The diameter of the cylinder is 160 mm or 200 mm.

26. A battery cell, wherein: include: Shell components; A pole component is provided on the housing component, and the pole component includes a conductive portion; an electrode assembly housed in the housing component and comprising a tab portion, the tab portion comprising a plurality of tab sheets stacked together, the plurality of tab sheets being connected to form a gathered portion, the gathered portion being stacked and connected to the conductive portion to form a connecting portion; Wherein, the gathered portion includes a compacted area, the thickness of the compacted area is less than the stacking thickness of the multiple pole tab sheets in the pole tab portion, the connecting portion includes a first part formed in the gathered portion, at least most of the contour line of the first part is located in the compacted area, the gathered portion is processed by the ultrasonic welding device according to any one of claims 23-25 ​​and the compacted area is processed by the welding teeth.

27. The battery cell according to claim 26, wherein: The connecting portion extends from the outer surface of the gathered portion toward the conductive portion. The first portion includes a surface portion formed on the outer surface of the gathered portion, and more than 60% of the contour line of the surface portion falls within the compacted area.

28. The battery cell according to claim 26 or 27, wherein: The compaction rate of the compacted area is greater than or equal to 6%.

29. The battery cell according to claim 28, wherein The compaction rate of the compacted area is greater than or equal to 12%.

30. A battery, wherein: The invention comprises a battery cell according to any one of claims 26 to 29.

31. An electrical device, wherein: Comprising a battery according to claim 30.

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