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 equipment, battery cell, battery and electrical device

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202420691915.0, filed on April 3, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This 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 Technology

[0004] In recent years, new energy vehicles have experienced rapid development. In the field of electric vehicles, the power battery, as the power source, plays an irreplaceable and crucial role. The power battery comprises several individual battery cells; however, the reliability of these individual cells needs improvement.

[0005] Summary of the Invention

[0006] This application provides a battery cell, a battery, and an electrical device that can improve the reliability of the battery cell.

[0007] In a first aspect, embodiments of this application provide a welding head, the welding end of which has welding teeth and tooth grooves, the welding teeth being divided into multiple spaced tooth sections by the tooth grooves, and the tooth area of ​​the welding end accounting for more than or equal to 40%.

[0008] In the above technical solution, by setting the area ratio of the teeth at the welding end to not less than 40%, the area ratio of the compacted region in the ultrasonic welding can be increased, so that the outline of the laser welding falls more into the compacted region, thereby improving the problem of thermal cracking in the outline of the laser welding to a greater extent, thereby improving the conductivity and connection strength of the tab 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 in an intersecting manner. There are multiple first straight grooves arranged in parallel. A tooth is defined between adjacent first straight grooves and second straight grooves. The groove width of the first straight groove and the groove width of the second straight groove are both smaller than the distance between adjacent first straight grooves.

[0010] In the above technical solution, the welding teeth are divided by straight grooves, which makes the teeth easy to process and reduces processing costs. Moreover, it helps to reduce the area ratio of the teeth and increase the area of ​​the teeth confined between adjacent first and second straight grooves. This helps to increase the area ratio of the teeth at the welding end, allowing the outline of the laser welding to fall more into the compaction area, further improving the problem of thermal cracking in the outline of the laser welding, thereby improving the conductivity and connection strength of the tab and conductive part, and enhancing the reliability of the battery cell.

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

[0012] The above technical solution is beneficial to improving the gripping force during welding, providing greater friction, and increasing the tooth area ratio at the welding end.

[0013] In some embodiments, there are multiple second straight grooves arranged in parallel, and a toothed portion is defined between adjacent first straight grooves and adjacent second straight grooves. The groove width of the first straight groove and the groove width of the second straight groove are both smaller than the distance between adjacent second straight grooves.

[0014] In the above technical solution, by setting multiple parallel first straight grooves and multiple parallel second straight grooves, multiple teeth can be easily constructed due to the intersecting arrangement of the first and second straight grooves, making the welding head easier to process. Furthermore, it helps to reduce the area ratio of the grooves and increase the area of ​​the teeth confined between adjacent first and second straight grooves, thereby increasing the tooth area ratio at the welding end. This allows the laser weld outline to fall more into the compaction area, further improving the problem of thermal cracking in the laser weld outline, and ultimately improving the conductivity yield and connection strength between the tab and the conductive part, thus enhancing the reliability of the battery cell.

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

[0016] The above technical solution is beneficial to improving the gripping force during welding, providing greater friction, and increasing the tooth area ratio at the welding end.

[0017] In some embodiments, the welding end is elongated, 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 axially symmetrical with respect to the width direction of the welding end, and the tooth area accounts for 40%-50%.

[0018] In the above technical solution, the welding head has a simple structure and is easy to process. The area occupied by the first and second straight grooves is relatively small, which can increase the tooth area ratio of the welding end to 40%-50%. This allows the outline of the laser welding to fall more into the compaction area, thereby improving the problem of thermal cracking in the outline of the laser welding to a greater extent. This, in turn, improves the conductivity and connection strength of the tab and the conductive part, and enhances the reliability of the battery cell.

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

[0020] In the above technical solution, the area of ​​the first tooth is relatively large, which is beneficial to achieving a tooth area ratio of 40%-50% and to meeting the gripping force requirements, thus providing greater friction. Moreover, the welding head has a simple structure, is easy to process, and has low manufacturing cost.

[0021] In some embodiments, the welding end is elongated, 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 the tooth area accounts for 50%-60%.

[0022] In the above technical solution, the welding head has a simple structure and is easy to process. Setting the length direction of the first straight groove to be parallel to the width direction of the welding end and setting the length direction of the second straight groove to be parallel to the length direction of the welding end helps to increase the tooth area ratio of the welding end, so that the tooth area ratio reaches 50%-60%. This allows the outline of the laser welding to fall more into the compaction area, thereby improving the problem of thermal cracking in the outline of the laser welding to a greater extent. This, in turn, improves the conductivity and connection strength of the tab and the conductive part, and enhances the reliability of the battery cell.

[0023] In some embodiments, the tooth portion includes a second tooth portion defined between an adjacent first straight groove and an adjacent second straight groove, the tooth tip size of the second tooth portion in the first straight groove spacing direction is 1.5mm-2.4mm, and the tooth tip 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 has a larger area, which is beneficial for achieving a tooth area ratio of 50%-60% and for meeting the gripping force requirements, thus providing greater friction. Moreover, the welding head has a simple structure, is easy to process, and has low manufacturing cost.

[0025] In some embodiments, the welding end is elongated, 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 located at the center of the width of the welding end, and the tooth area accounts for 60%-70%.

[0026] The above technical solution helps reduce the proportion of grooves and significantly increases the tooth area ratio at the welding end, reaching 60%-70%. This allows the laser weld outline to fall more into the compaction area, thus mitigating the problem of thermal cracking in the laser weld outline and improving the conductivity and connection strength of the tab and conductive part, thereby enhancing the reliability of the battery cell. Furthermore, because the number of second straight grooves is relatively small, the area of ​​the teeth between adjacent first and second straight grooves is larger, which helps increase the volume of the molten pool falling into the compaction area, thereby reducing porosity in the molten pool and improving the current-carrying capacity of the laser weld.

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

[0028] In the above technical solution, the third tooth is an elongated strip-shaped tooth extending along the width direction of the welding end. The larger area of ​​the third tooth facilitates achieving a tooth area ratio of 60%-70% and meets the gripping force requirements, 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 direction of the ultrasonic weld mark, two rows of these elongated third teeth are provided on the welding end. This reduces the volume of the laser weld mark falling into the fluffy area in the width direction of the ultrasonic weld mark, thereby reducing porosity in the molten pool and improving the flow capacity of the laser weld mark.

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

[0030] In the above technical solution, when the laser weld mark is a long strip extending along the length direction of the ultrasonic weld mark, the width of the first straight groove is set to be smaller than the 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 outline pass, which is beneficial to improving the problem of cracking in the outline of the laser weld mark.

[0031] In some embodiments, the welding end is elongated, 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 teeth portions, which are spaced apart along the width direction of the welding end.

[0032] In the above technical solution, by setting the fourth tooth as an elongated shape matching the length direction of the welding end, and arranging several elongated fourth teeth along the width direction of the welding end, it is beneficial to increase the area of ​​a single fourth tooth, thereby increasing the tooth area ratio of the welding end. This allows the outline of the laser weld to fall more into the compaction area. Furthermore, when the laser weld is constructed as an elongated shape extending along the length direction of the ultrasonic weld, the two long sides of the laser weld outline can fall more into the compaction area corresponding to the fourth tooth, which helps to improve the problem of cracking in the outline of the laser weld.

[0033] In some embodiments, there are two fourth teeth spaced apart along the width direction of the welding end. The ratio of the tooth tip length of the fourth tooth in the length direction of the welding end to the length of the welding end is 75%-85%, the ratio of the tooth tip width of the fourth tooth in the width direction of the welding end to half 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 increase the tooth area ratio at the welding end, reaching 70%-80%. This allows more of the molten pool of the laser weldment to fall into the compaction area, thereby reducing porosity in the molten pool and improving the flow capacity of the laser weldment. Furthermore, when the laser weldment is constructed as an elongated strip extending along the length of the ultrasonic weldment, the two long sides of the laser weldment outline can fall into the compaction areas corresponding to the two fourth teeth, which is beneficial for laser weldment placement and improves the problem of cracking in the laser weldment outline.

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

[0036] In the above technical solution, each long side of the fourth tooth is uneven, which helps to improve the gripping force during welding and provide greater friction, so that the fourth tooth can effectively compact the electrode tabs, improve the compaction rate of the compaction area corresponding to the fourth tooth, and further improve the problem of cracks appearing in the contour of the laser welding print.

[0037] In some embodiments, the welding tooth further includes a plurality of fifth teeth disposed between the two fourth teeth and spaced apart along the length direction of the welding end. The protrusions of the two fourth teeth are positioned opposite each other on one side, and two opposing protrusions are disposed between each pair of adjacent fifth teeth. The contour lines of the fourth teeth match the contour lines of the fifth teeth.

[0038] In the above technical solution, welding teeth can be constructed by further utilizing the welding end, increasing the area of ​​the fourth and fifth teeth, and improving the tooth area ratio of the welding end. When the two long sides of the laser weld mark are respectively located in the compaction area corresponding to the two fourth teeth, the laser weld mark can also cover at least part of the compaction area corresponding to multiple fifth teeth, thereby increasing the portion of the laser weld mark falling in the compaction area, further improving the problem of porosity in the molten pool of the laser weld mark, and further improving the conductivity yield of the convergence part and the conductive part.

[0039] In some embodiments, the welding tooth includes a plurality of sixth teeth, which are arranged in a plurality of spaced-apart configurations surrounding two fourth teeth, the profiles of the fourth teeth matching the profiles of the sixth teeth.

[0040] In the above technical solution, by setting multiple sixth teeth around the two fourth teeth, and because the contour lines of the sixth teeth match the contour lines of the fourth teeth, that is, the protruding position of the contour of the fourth teeth corresponds to the concave position of the contour of the sixth teeth, it helps to improve the gripping force during welding, so as to provide greater friction, enabling the fourth teeth to effectively compact the electrode tabs, improve the compaction rate of the compaction area corresponding to the fourth teeth, and further improve the problem of cracks appearing in the contour of laser welding.

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

[0042] In the above technical solution, by setting the size of the protrusion as described above, it is beneficial to improve the gripping force during welding, so as to provide greater friction and enable the fourth tooth to effectively compact the electrode tab.

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

[0044] In the above technical solution, the groove width is smaller, which can reduce the proportion of the groove on the welding end, thereby increasing the proportion of the welding teeth and thus increasing the proportion of the compacted area on the closing part.

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

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

[0047] In some embodiments, the tooth height is less than or equal to 2.5 mm, and the projected distance between the tooth tip and the tooth root is 0.1 mm to 0.2 mm.

[0048] In the above technical solution, the side of the tooth has a certain inclination, which facilitates the improvement of the compaction rate and reduces the edge sharpness of the tooth to improve the problem of scratching the electrode tab.

[0049] In some embodiments, the edges of the welded ends are rounded, and the radius of the rounded corners is 0.5mm-2mm.

[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 electrode tab can be improved, which is conducive to the smooth progress of welding and improves the connection reliability and conductivity between the electrode tab and the conductive part.

[0051] Secondly, embodiments of this application also provide an ultrasonic welding device, including a drive cylinder, a welding base, and a welding head according to any of the above-described schemes. The drive cylinder is located on the side of the welding head away from the welding base and is used to drive the welding head to move toward the welding base.

[0052] In the above technical solution, since the welding head according to the embodiment of this application is beneficial to increasing the area of ​​the compacted region in the ultrasonic weld, the weld in which the ultrasonic welding device is used has a larger compacted region, which is beneficial to improving the subsequent laser welding effect between the electrode tab and the conductive part.

[0053] In some embodiments, the drive cylinder is a pneumatic cylinder with a diameter 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 hot cracking in the outline of the laser weld, improving the conductivity and connection strength of the tab and conductive part, reducing the porosity in the molten pool of the laser weld, improving the current carrying capacity of the laser weld, and enhancing the reliability of the battery cell.

[0055] In some embodiments, the cylinder diameter is 160 mm or 200 mm.

[0056] In the above technical solution, the cylinder is relatively easy to process and can be put into operation. Moreover, the compaction rate of the compaction area is high, which can effectively improve the problem of thermal cracking in the contour of the laser welding, improve the conductivity and connection strength of the tab and the conductive part, reduce the porosity in the molten pool of the laser welding, improve the current carrying capacity of the laser welding, and improve the reliability of the battery cell.

[0057] Thirdly, embodiments of this application also provide a battery cell, including: a housing component, a terminal component, and an electrode assembly. The terminal component is disposed on the housing component and includes a conductive portion. The electrode assembly is housed in the housing component and includes a tab portion. The tab portion includes a plurality of tabs stacked together. The plurality of tabs are connected to form a converged portion. The converged portion is stacked with and connected to the conductive portion to form a connecting portion. The converged portion includes a compacted region. The thickness of the compacted region is less than the stacking thickness of the plurality of tabs in the tab portion. The connecting portion includes a first portion formed in the converged portion. At least a majority of the outline of the first portion is located in the compacted region. The converged portion is processed by an ultrasonic welding device including any of the above-mentioned schemes, and the compacted region is processed by welding teeth.

[0058] In the above technical solution, since at least part of the outline of the portion of the connecting part formed on the converging part is located in the compaction area, the multi-layer electrode tabs in the compaction area are very tightly bonded together, which helps to improve the problem of cracks appearing in the outline of the connecting part, improves the conductivity and connection strength of the electrode tab and the conductive part, and enhances the overcurrent capacity and reliability of the battery cell.

[0059] In some embodiments, the connecting portion extends from the outer surface of the retractable portion toward the conductive portion, and the first portion includes a surface portion formed on the outer surface of the retractable portion, wherein more than 60% of the outline of the surface portion falls within the compacted area.

[0060] In the above technical solution, by setting the extension direction of the connecting part to be from the converging part to the conductive part, it is easier for the welding head to align with the converging part. This allows the welding head to rationally design the welding trajectory based on the distribution of the compacted and loose areas on the converging part, and accurately weld along the welding trajectory. This ensures that at least a majority of the outline of the portion of the connecting part formed on the converging part can reliably lie in the compacted area, thereby effectively improving the conductivity and connection strength between the tab and the conductive part, and enhancing the current carrying capacity and reliability of the battery cell. Furthermore, by setting more than 60% of the outline of the surface portion to fall within the compacted area, the problem of cracking in the weld outline of the connecting part on the surface of the converging part can be further improved. In addition, since the connecting part extends from the outer surface of the converging part towards the conductive part, the outline of the internal portion can extend from the outline of the surface portion towards the conductive part. When more than 60% of the outline of the surface portion falls within the compacted area, it is beneficial to further increase the proportion of the internal portion's outline falling within the compacted area relative to falling within the loose area, thereby further improving the problem of cracking in the outline of the first part of the connecting part formed on the converging part.

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

[0062] In the above technical solution, by setting the compaction rate of the compaction zone to be greater than or equal to 6%, the interlayer gap in the compaction zone can be reduced, the part of the connector entering the compaction zone is less prone to thermal cracks and pores, the overall flow capacity of the connector is improved, and the reliability and conductivity of the connector connecting the conductive part and the gathering part are enhanced.

[0063] In some embodiments, the compaction rate of the compacted area 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, making the compaction area almost gapless. The part of the connector that enters the compaction area is less prone to thermal cracks and pores, thereby improving the overall flow capacity of the connector and the reliability and conductivity of the connector connecting the conductive part and the gathering part.

[0065] Fourthly, embodiments of this application also provide a battery, including a battery cell of any of the above-described solutions.

[0066] In the above technical solution, the reliability of the battery cell according to the embodiment of this application is improved, which is beneficial to improving the reliability of the battery.

[0067] Fifthly, embodiments of this application also provide an electrical device including a battery from any of the above-described solutions.

[0068] In the above technical solution, the improved reliability of the battery helps to improve the power consumption performance of the electrical device. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 is a structural schematic diagram of a vehicle provided in some embodiments of this application;

[0071] Figure 2 is an exploded view of the battery structure provided in some embodiments of this application;

[0072] Figure 3 is a perspective view of a battery cell provided in some embodiments of this application;

[0073] Figure 4 is a top view of a battery cell provided in some embodiments of this application;

[0074] Figure 5 is a cross-sectional view along line AA in Figure 4;

[0075] Figure 6 is a magnified view of part B in Figure 5;

[0076] Figure 7 is a partial cross-sectional view of the welding of the electrode tab and the conductive part according to some embodiments of this application;

[0077] Figure 8 is a schematic diagram of ultrasonic pre-welding of the electrode tab by an ultrasonic welding device provided in some embodiments of this application;

[0078] Figure 9 is a magnified view of part C in Figure 8;

[0079] Figure 10 is a partial cross-sectional view of the welding of the electrode tab and the conductive part according to some embodiments of this application;

[0080] Figure 11 is a partial cross-sectional view of the welding of the electrode tab and the conductive part according to some embodiments of this application;

[0081] Figure 12 is a partial schematic diagram of a welding head provided in some embodiments of this application;

[0082] Figure 13 is a schematic diagram of the welding end of the welding head provided in some embodiments of this application;

[0083] Figure 14 is a schematic diagram of the welding end of the welding head provided in some other embodiments of this application;

[0084] Figure 15 is a schematic diagram of the welding end of the welding head provided in some embodiments of this application;

[0085] Figure 16 is a schematic diagram of the welding end of a welding head provided in some embodiments of this application;

[0086] Figure 17 is a schematic diagram of the welding of the retractable portion and the conductive portion according to some embodiments of this application;

[0087] Figure 18 is a front view of an ultrasonic welding apparatus provided in some embodiments of this application;

[0088] Figure 19 is a left view of the ultrasonic welding device shown in Figure 18;

[0089] Figure 20 is a partial cross-sectional view of the converging part in Comparative Example 1;

[0090] Figure 21 shows a partial cross-sectional view of the converging part and the conductive part after laser welding in Comparative Example 1.

[0091] Figure 22 is a partial cross-sectional view of the converging part in Comparative Example 2;

[0092] Figure 23 shows a partial cross-sectional view of the converging part and the conductive part after laser welding in Comparative Example 2.

[0093] Figure 24 is a partial cross-sectional view of the converging part in Comparative Example 3;

[0094] Figure 25 shows a partial cross-sectional view of the converging part and the conductive part after laser welding in Comparative Example 3.

[0095] Figure 26 is a partial cross-sectional view of the retractable part in Embodiment 1;

[0096] Figure 27 is a partial cross-sectional view of the retractable part and the conductive part after laser welding in Embodiment 1;

[0097] Figure 28 is a partial cross-sectional view of the retractable part in Embodiment 2;

[0098] Figure 29 is a partial cross-sectional view of the retractable part and the conductive part after laser welding in Embodiment 2;

[0099] Figure 30 is a partial cross-sectional view of the retractable part in Embodiment 3;

[0100] Figure 31 is a partial cross-sectional view of the retractable part and the conductive part after laser welding in Embodiment 3;

[0101] Figure 32 is a partial cross-sectional view of the retractable part in Embodiment 4;

[0102] Figure 33 is a partial cross-sectional view of the retractable part and the conductive part after laser welding in Example 4;

[0103] Figure 34 is a topographic image of the ultrasonic weld mark processed by the welding head shown in Figure 13.

[0104] Figure 35 is a cross-sectional morphology diagram of the ultrasonic solder mark shown in Figure 34;

[0105] Figure 36 is a topographical diagram of the ultrasonic weld mark processed by the welding head shown in Figure 14.

[0106] Figure 37 is a cross-sectional topography of the ultrasonic solder mark shown in Figure 36;

[0107] Figure 38 is a topographical diagram of the ultrasonic weld mark processed by the welding head shown in Figure 15.

[0108] Figure 39 is a cross-sectional morphology diagram of the ultrasonic solder mark shown in Figure 38;

[0109] Figure 40 is a topographical diagram of the ultrasonic weld mark processed by the welding head shown in Figure 16.

[0110] Figure 41 is a cross-sectional topographic view of the ultrasonic weld mark shown in Figure 40.

[0111] Figure label:

[0112] 1000 vehicles;

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

[0114] Box 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] Shell component 1; first shell wall 11; receiving cavity 12;

[0118] 2. Terminal component 2; Conductive part 20; Terminal body 21;

[0119] Electrode assembly 3; Active material coating part 31; Electrode tab part 32; Electrode tab plate 320;

[0120] Gathered area 321; Compacted area 3211; Fluffy area 3212;

[0121] Connecting part 4; First part 41; Surface part 411; Outline 4x of surface part 411;

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

[0123] Internal portion 412; outline 4y of internal portion 412; second portion 42;

[0124] First connecting part 4a; Second connecting part 4b; Third connecting part 4c;

[0125] Ultrasonic welding equipment 2000;

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

[0127] First tooth 511; Second tooth 512; Third tooth 513;

[0128] Fourth tooth 514; Protrusion 5141; Fifth tooth 515; Sixth tooth 516;

[0129] First tooth 5161; Second tooth 5162;

[0130] Gear groove 6; First straight groove 61; Second straight groove 62;

[0131] First partition groove 63; Second partition groove 64;

[0132] 500mm welding base; 600mm drive cylinder. Detailed Implementation

[0133] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0134] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

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

[0136] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0137] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

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

[0139] In this application, "multiple" means two or more (including two).

[0140] In this application, the battery cell 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 are not limited to these. The battery cell may be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited to these. Battery cells are generally divided into three types according to their packaging method: cylindrical battery cells, square battery cells, and pouch battery cells, and the embodiments of this application are not limited to these.

[0141] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned 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 housing for encapsulating one or more battery cells or one or more battery modules. The housing can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0142] A single battery cell includes a casing, electrode assemblies, and electrolyte. The casing houses the electrode assemblies and electrolyte. The casing contains at least one electrode assembly, which consists of a positive electrode, a negative electrode, and a separator. The electrode assembly can be a wound structure or a stacked structure, etc. The battery cell primarily functions by the movement of metal ions between the positive and negative electrode assemblies.

[0143] A positive electrode typically includes a positive current collector and a positive active material layer. The positive active material layer is directly or indirectly coated onto the positive current collector. The positive current collector without a positive active material layer protrudes from the one with a positive active material layer, serving as the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the material of the positive active material layer can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc.

[0144] A negative electrode typically includes a negative current collector and a negative active material layer. The negative active material layer is directly or indirectly coated onto the negative current collector. The negative current collector without a negative active material layer protrudes from the negative current collector with a negative active material layer, and the negative current collector without a negative active material layer serves as the negative electrode tab. The material of the negative current collector can be copper, and the material of the negative active material layer can be carbon or silicon, etc.

[0145] To ensure that a large current can be passed without melting, multiple positive electrode tabs are stacked together to form the positive electrode tab portion, and multiple negative electrode tabs are stacked together to form the negative electrode tab portion. A terminal component is provided on the housing component; the positive electrode tab portion is electrically connected to the positive electrode terminal component, and the negative electrode tab portion is electrically connected to the negative electrode terminal component.

[0146] In related technologies, ultrasonic welding is used to connect multiple tabs in the electrode section to form an ultrasonic weld mark. Then, laser welding is used to weld the ultrasonic weld mark to the conductive part of the terminal component, realizing the connection and electrical conduction between the electrode assembly and the terminal component. However, the profile of the laser weld has the problem of thermal cracking, which affects the conductivity yield and connection strength between the tab and the conductive part, and affects the reliability of the battery cell.

[0147] To address this, embodiments of this application propose a welding head 400. The welding end of the welding head 400 has welding teeth and grooves. The welding teeth are divided into multiple spaced tooth sections by the grooves, and the area ratio of the teeth at the welding end is greater than or equal to 40%. Therefore, by setting the area ratio of the teeth at the welding end to not less than 40%, the area ratio of the compacted region in the ultrasonic welding process can be increased, allowing the contour of the laser weld to fall more into the compacted region. Since the multi-layered tabs in the compacted region can be tightly bonded together, this helps to improve the problem of thermal cracking and deterioration of the laser weld contour, thereby improving the conductivity and connection strength between the tabs and the conductive parts, and enhancing the reliability of the battery cell.

[0148] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0149] For ease of explanation, the following embodiments will be described using a vehicle as an example of an electrical device according to an embodiment of this application.

[0150] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 1000, and the battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the 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 supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0151] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the 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 a battery 100 provided in some embodiments of this application. The battery 100 includes a housing 101 and a plurality of battery cells 102, with the battery cells 102 housed within the housing 101. The housing 101 provides assembly space for the battery cells 102, and the housing 101 can adopt various structures. In some embodiments, the housing 101 may include a first housing body 1011 and a second housing body 1012, which overlap each other, and together define an assembly space for accommodating the battery cells 102. The second box body 1012 can be a hollow structure open at one end, and the first box body 1011 can be a plate-shaped cover structure. The first box body 1011 covers the open side of the second box body 1012, so that the first box body 1011 and the second box body 1012 together define the assembly space. Alternatively, the first box body 1011 and the second box body 1012 can both be hollow structures open on one side, with the open side of the first box body 1011 covering the open side of the second box body 1012. Of course, the box 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 battery 100, multiple battery cells 102 can be connected in series, parallel, or in a hybrid configuration. A hybrid configuration means that multiple battery cells 102 are connected in both series and parallel configurations. Multiple battery cells 102 can be directly connected in series, parallel, or in a hybrid configuration, and then the entire assembly of the multiple battery cells 102 is housed within housing 101. Alternatively, battery 100 can also be composed of multiple battery cells 102 first connected in series, parallel, or in a hybrid configuration to form a battery module, and then multiple battery modules are connected in series, parallel, or in a hybrid configuration to form a whole, which is also housed within housing 101. Battery 100 may also include other structures; for example, battery 100 may also include a busbar component for electrically welding multiple battery cells 102.

[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 to these. The battery cell 102 can be cylindrical, flat, cuboid, etc. For example, referring to the embodiment shown in Figure 3, the length direction of the battery cell 102 is the first direction X, the width direction of the battery cell 102 is the second direction Y, and the height direction of the battery cell 102 is the third direction Z. The first direction X, the second direction Y, and the third direction Z are all perpendicular to each other.

[0155] Please refer to Figures 3-7. Figure 3 is a perspective view of a battery cell 102 provided in some embodiments of this application. Figure 4 is a top view of the battery cell 102 shown in Figure 3. Figure 5 is a cross-sectional view along line AA in Figure 4. Figure 6 is a partial enlarged view of part B in Figure 5. Figure 7 is a partial cross-sectional view of the connection between the conductive part 20 and the gathering part 321 provided in some embodiments of this application. In some embodiments of this application, the battery cell 102 includes: a housing component 1, a terminal component 2, and an electrode assembly 3. The terminal component 2 is disposed on the housing component 1 and includes a conductive part 20. The electrode assembly 3 is housed in the housing component 1 and includes a tab part 32. The tab part 32 includes a plurality of tab pieces 320 stacked together. The plurality of tab pieces 320 are connected to form a gathering part 321. The gathering part 321 is stacked with the conductive part 20 and connected to form a connecting part 4.

[0156] For example, referring to Figures 3-6, the housing component 1 may include a first housing wall 11, and the pole member 2 is disposed on the first housing wall 11. The structure of the housing component 1 is not limited. For example, the housing component 1 may include a housing body and a housing cover, the housing body defining a cavity closed at one end and open at the other, and the housing cover covering the open end of the housing body. The housing cover may serve as the first housing wall 11, or the wall surface of the housing body opposite to the housing cover may also serve as the first housing wall 11. As another example, the housing component 1 may include two half-shells joined together, each half-shell defining a cavity open toward the other half-shell, with the wall surface of one half-shell away from the other half-shell serving as the first housing wall 11.

[0157] Referring to Figures 5 and 6, the electrode post component 2 includes a conductive part 20, which is the portion of the electrode post component 2 used to connect with the electrode assembly 3. For example, the conductive part 20 can be the electrode post body 21. In this case, the folded portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the electrode post body 21. Alternatively, the conductive part 20 can also be an adapter piece connected to the electrode post body 21. In this case, the folded portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the adapter piece, and the adapter piece is electrically connected to the electrode post body 21. Thus, the folded portion 321 is indirectly electrically connected to the electrode post body 21 through the adapter piece. For simplicity, the following description will mainly use the electrode post body 21 as an example for the conductive part 20.

[0158] Referring to Figures 5 and 6, the electrode assembly 3 includes an active material coating portion 31 housed within the housing component 1, and an electrode tab portion 32 connected to the active material coating portion 31. Exemplarily, a receiving cavity 12 is formed inside the housing component 1, the active material coating portion 31 is housed within the receiving cavity 12, the electrode post body 21 passes through the first housing wall 11, and the electrode tab portion 32 is welded to the electrode post body 21. The electrode tab portion 32 and the electrode post body 21 are directly electrically connected, such that the electrode tab portion 32 is electrically connected between the active material coating portion 31 and the electrode post body 21.

[0159] For example, referring to Figures 6 and 7, multiple tabs 320 in the tab portion 32 are stacked. The multiple tabs 320 are ultrasonically welded to form a convergence portion 321. That is, the part where multiple tabs 320 are connected together by ultrasonic welding is the ultrasonic weld mark. The ultrasonic weld mark constitutes the convergence portion 321. Therefore, the multiple tabs 320 in the convergence portion 321 not only have a stacked arrangement but also a connected relationship. The thick side surface of the convergence portion 321 faces the conductive portion 20 and is disposed on the conductive portion 20 to realize the stacking of the convergence portion 321 and the conductive portion 20. The convergence portion 321 and the conductive portion 20 are connected together by laser welding. The laser weld seam constitutes the connection portion 4 connecting the conductive portion 20 and the convergence portion 321.

[0160] In the embodiments of this application, referring to Figures 7-9, the gathering portion 321 includes a compacted region 3211. The thickness T1 of the compacted region 3211 is less than the theoretical thickness T2 of the tab portion 32. Since the thickness T1 of the compacted region 3211 of the gathering portion 321 is less than the theoretical thickness T2 of the tab portion 32, it indicates that the tab 320 in the compacted region 3211 is compressed and yielded and undergoes plastic deformation. The thickness of the tab 320 is reduced, and the multiple tabs 320 in the compacted region 3211 are tightly bonded together with no or almost no interlayer gaps. The compaction rate of the gathering portion 321 is greater than 0%.

[0161] The "compaction rate" of the gathering 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 stacking thickness of multiple tabs 320 in the tab portion 32, i.e., the thickness of the tabs 320 without compression and stacked together in multiple layers without gaps. For example, if the thickness of a single tab 320 is a (i.e., a is the thickness of a single layer of foil), and b layers of tabs 320 are stacked in the tab portion 32 (i.e., b is the number of layers of foil), then the stacking thickness of multiple layers of tabs 320 in the tab portion 32 is a×b. Therefore, the theoretical thickness T2 of the tab portion 32 is a×b.

[0162] For example, referring to Figures 8 and 9, the gathering part 321 is processed by ultrasonic welding. The welding head 400 used in the ultrasonic welding process has welding teeth 5 and tooth grooves 6. The welding teeth 5 are divided into multiple tooth parts 51 spaced apart by the tooth grooves 6. That is, the tooth grooves 6 are the inter-tooth gaps between the multiple tooth parts 51 of the welding teeth 5. After welding, the area on the gathering part 321 corresponding to the tooth parts 51 is the compacted area 3211, and the area on the gathering part 321 corresponding to the tooth grooves 6 is the fluffy area 3212. The multi-layer tabs 320 in the compacted area 3211 are effectively welded together, and there are no or almost no interlayer gaps between the foils. The multi-layer tabs 320 in the fluffy area 3212 are not effectively fused together, and there are interlayer gaps between the multi-layer tabs 320.

[0163] In the embodiments of this application, referring again to Figures 6 and 7, 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, referring to FIG7, when laser welding is performed from the side of the gathering portion 321 away from the conductive portion 20, the first portion 41 of the connecting portion 4 formed on the gathering portion 321 may include: a surface portion 411 formed on the outer surface of the gathering portion 321, and an inner portion 412 formed within the gathering 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 away from the gathering portion 321, the first portion 41 of the connecting portion 4 formed on the gathering portion 321 may only include: the inner portion 412 formed within the gathering 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 connecting part 4 is a long strip laser weld, the outline 4x of the surface part 411 can be a rectangular frame formed by two long sides 4x1 and two short sides 4x2.

[0166] The outline of the first part 41 can fall entirely within the compacted region 3211, meaning the entire outline of the portion of the connecting part 4 formed on the closing part 321 can be located within the compacted region 3211. Alternatively, the outline of the first part 41 can fall partly within the compacted region 3211 and the remainder within the loose region 3212, meaning a portion of the outline of the connecting part 4 formed on the closing part 321 falls within the compacted region 3211, and the remainder falls within the loose region 3212. Because the multiple layers of tabs 320 in the compacted region 3211 are very tightly bonded together with little or no interlayer gaps, the outline falling within the compacted region 3211 is less prone to thermal cracking, resulting in better conductivity and connection reliability between the conductive part 20 and the closing part 32.

[0167] In the embodiments of this application, when the connecting part 4 is a laser weld, it may include only one weld, completed in one welding operation, or it may include multiple overlapping welds, completed in multiple welding operations. In this case, the total weld formed by the fusion of the multiple welds constitutes the connecting part 4. For example, referring to FIG10, the laser weld may include a root weld (e.g., the first connecting part 4a marked in FIG10), a main weld (e.g., the second connecting part 4b marked in FIG10), and a repair weld (e.g., the third connecting part 4c marked in FIG10) welded sequentially. In this case, the total weld formed by the fusion of the three welds constitutes the connecting part 4. As another example, referring to FIG11, the repair weld may be omitted, and the root weld (e.g., the first connecting part 4a marked in FIG11) and the main weld (e.g., the second connecting part 4b marked in FIG11) may be welded sequentially. In this case, the total weld formed by the fusion of these two welds constitutes the connecting part 4. For example, referring to Figure 7, the repair weld and the root weld can be omitted, and only one main weld (e.g., the second connection part 4b marked in Figure 7) can be welded, which constitutes the connection part 4.

[0168] Referring to Figures 12 and 13, an embodiment of this application proposes a welding head 400. The welding end 401 of the welding head 400 has welding teeth 5 and tooth grooves 6. The welding teeth 5 are divided into a plurality of spaced teeth 51 by the tooth grooves 6. The area ratio of the teeth of the welding end 401 is greater than or equal to 40%. It is worth noting that "the area ratio of the teeth 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 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 area of ​​the tooth grooves on the welding end to the toothless area of ​​the welding end 401.

[0169] Therefore, by setting the area ratio of the teeth at the welding end 401 to not less than 40%, the area ratio of the compacted area 3211 in the ultrasonic welding can be increased, so that the outline of the laser weld falls more into the compacted area 3211, thereby improving the problem of thermal cracking in the outline of the laser weld to a greater extent, thereby improving the conductivity and connection strength between the tab 32 and the conductive part 20, and enhancing the reliability of the battery cell 102.

[0170] In some embodiments of this application, as shown in Figures 12 and 13, the tooth groove 6 includes intersecting first straight grooves 61 and second straight grooves 62. Multiple first straight grooves 61 are arranged in parallel, and a tooth 51 is defined between adjacent first straight grooves 61 and second straight grooves 62. Exemplarily, since adjacent first straight grooves 61 are arranged in parallel, the tooth 51 defined between two adjacent first straight grooves 61 and second straight grooves 62 can be polygonal. Two adjacent first straight grooves 61 and the second straight groove 62 intersecting with these two first straight grooves 61 can form the three sides of a tooth 51. Thus, by dividing the welding teeth 5 with straight grooves, the tooth groove 6 is easier to process, which helps reduce the processing cost of the welding head 400 and improves the processing efficiency of the welding head 400.

[0171] As shown in Figure 13, the width W1 of the first straight groove 61 and the width W2 of the second straight groove 62 are both smaller than the distance D1 between adjacent first straight grooves 61. The tooth 51, which is defined between adjacent first straight grooves 61 and second straight grooves 62, has a dimension in the spacing direction of the first straight grooves 61 equal to the distance D1 between adjacent first straight grooves 61. This dimension is greater than both the width W1 of the first straight groove 61 and the width W2 of the second straight groove 62.

[0172] This helps to reduce the area ratio of the tooth groove 6 and increase the area of ​​the tooth portion 51 limited between the adjacent first straight groove 61 and second straight groove 62, thereby increasing the area ratio of the tooth at the welding end 401. This allows the outline of the laser weld to fall more into the compaction area 3211, further improving the problem of hot cracking in the outline of the laser weld, thereby improving the conductivity and connection strength of the tab portion 32 and the conductive portion 20, and enhancing the reliability of the battery cell 102.

[0173] In some embodiments of this application, as shown in FIG13, the spacing D1 between adjacent first straight grooves 61 is 1.5mm-2.5mm. For example, the spacing D1 between adjacent first straight grooves 61 can be 1.5mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, etc. Therefore, the spacing D1 between adjacent first straight grooves 61 is not too large, which is beneficial to improving the gripping force during welding; the spacing D1 between adjacent first straight grooves 61 is not too small, so that the size of the tooth 51 limited between the adjacent first straight groove 61 and the second straight groove 62 is not too small, which is beneficial to increasing the tooth area ratio of the welding end 401.

[0174] In some embodiments of this application, as shown in FIG13, there are multiple second straight grooves 62 arranged in parallel, and a tooth 51 is defined between adjacent first straight grooves 61 and adjacent second straight grooves 62. Exemplarily, since adjacent first straight grooves 61 are arranged in parallel, adjacent second straight grooves 62 are also arranged in parallel. The tooth 51 defined between two adjacent first straight grooves 61 and two adjacent second straight grooves 62 can be quadrilateral. Two adjacent first straight grooves 61 and two adjacent second straight grooves 62 that intersect with each of the two first straight grooves 61 can form the four sides of a tooth 51. Therefore, by providing multiple parallel first straight grooves 61 and multiple parallel second straight grooves 62, since the first straight grooves 61 and second straight grooves 62 are intersecting, multiple teeth 51 can be easily constructed, making the welding head 400 easy to process.

[0175] As shown in Figure 13, the width W1 of the first straight groove 61 and the width W2 of the second straight groove 62 are both smaller than the distance D2 between adjacent second straight grooves 62. Therefore, the dimension of the tooth 51 between adjacent first straight grooves 61 and adjacent second straight grooves 62 in the spacing direction of the second straight grooves 62 is equal to the distance D2 between adjacent second straight grooves 62. This dimension is greater than both the width W1 of the first straight groove 61 and the width W2 of the second straight groove 62.

[0176] This helps to reduce the area ratio of the tooth groove 6 and increase the area of ​​the tooth portion 51 limited between the adjacent first straight groove 61 and the adjacent second straight groove 62. This helps to increase the area ratio of the tooth at the welding end 401, so that the outline of the laser weld falls more into the compaction area 3211, further improving the problem of hot cracking in the outline of the laser weld, thereby improving the conductivity and connection strength of the tab portion 32 and the conductive portion 20, and enhancing the reliability of the battery cell 102.

[0177] In some embodiments of this application, as shown in FIG13, the spacing D2 between adjacent second straight grooves 62 is 1.5mm-2.5mm. For example, the spacing D2 between adjacent second straight grooves 62 can be: 1.5mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, etc. Thus, the spacing D2 between adjacent second straight grooves 62 is not too large, which is beneficial to improving the gripping force during welding; the spacing D2 between adjacent second straight grooves 62 is not too small, so that the size of the tooth 51 limited between the adjacent first straight groove 61 and the adjacent second straight groove 62 is not too small, thereby helping to increase the tooth area ratio of the welding end 401.

[0178] In some embodiments of this application, as shown in FIG13, the welding end 401 is elongated. The length direction of the first straight groove 61 intersects the length direction of the welding end 401 at an acute angle a1. The length direction of the second straight groove 62 is axially symmetrical to the length direction of the first straight groove 61 about the width direction of the welding end 401. Therefore, the included angle a2 and a1 of the intersection of the length direction of the second straight groove 62 and the length direction of the welding end 401 are equal. The tooth area ratio is 40%-50%, for example, the tooth area ratio is 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0179] For example, as shown in Figure 13, 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 straight groove 61 extends along the sixth direction M, and the length direction of the second straight 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 symmetrical about the fifth direction F. Thus, the multiple teeth 51 defined by the multiple first straight grooves 61 and the multiple second straight grooves 62 can present a diagonal grid pattern.

[0180] Therefore, the welding head 400 has a simple structure and is easy to process. Moreover, 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 to 40%-50%. This allows the outline of the laser weld to fall more into the compaction area 3211, thereby improving the problem of thermal cracking in the outline of the laser weld to a greater extent. This, in turn, improves the conductivity and connection strength between the tab 32 and the conductive part 20, and enhances the reliability of the battery cell 102.

[0181] Furthermore, when the laser weld seam is constructed as an elongated strip extending along the length direction of the ultrasonic weld (i.e., the length direction of the welding end 401), setting the length direction of the second straight groove 62 to be axially symmetrical with respect to the length direction of the first straight groove 61 about the width direction of the welding end 401 is advantageous compared to a scheme that achieves the same tooth area ratio of 40%-50% but does not set the length direction of the second straight groove 62 to be axially symmetrical with respect to the length direction of the first straight groove 61 about the width direction of the welding end 401. This is beneficial because the two long sides of the laser weld seam profile pass through the fluffy region 3212 less, which helps to improve the problem of hot cracking in the profile of the laser weld seam.

[0182] For example, referring to FIG13, the length direction (e.g., the sixth direction M) of the first straight groove 61 intersects the length direction (e.g., the fourth direction E) of the welding end 401 at a 45° angle. A tooth 51 defined between adjacent first straight grooves 61 and adjacent second straight grooves 62 is designated as a first tooth 511. The tooth tip dimension S1 of the first tooth 511 in the spacing direction of the first straight grooves 61 is 1.6mm-2mm, and the tooth tip dimension S2 of the first tooth 511 in the spacing direction of the second straight grooves 62 is also 1.6mm-2mm. Therefore, the first tooth 511 has a larger area, which is beneficial for achieving a tooth area ratio of 40%-50% and for meeting the gripping force requirements to provide greater friction. Furthermore, the welding head 400 has a simple structure, is easy to process, and has low manufacturing costs.

[0183] In some other embodiments of this application, as shown in FIG14, the welding end 401 is elongated, 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 ratio is 50%-60%, for example, the tooth area ratio is 50%, 52%, 54%, 56%, 58%, 60%, etc.

[0184] For example, as shown in Figure 14, 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 straight groove 61 is parallel to the fifth direction F, and the length direction of the second straight groove 62 is parallel to the fourth direction E. Thus, the multiple teeth 51 defined by the multiple first straight grooves 61 and the multiple second straight grooves 62 can present a grid pattern.

[0185] Therefore, the welding head 400 has a simple structure and is easy to process. Setting the length direction of the first straight groove 61 to be parallel to the width direction of the welding end 401 and setting the length direction of the second straight groove 62 to be parallel to the length direction of the welding end 401 is beneficial to increasing the tooth area ratio of the welding end 401, so that the tooth area ratio reaches 50%-60%. This allows the outline of the laser weld to fall more into the compaction area 3211, thereby improving the problem of hot cracking in the outline of the laser weld to a greater extent. This, in turn, improves the conductivity and connection strength between the tab 32 and the conductive part 20, and enhances the reliability of the battery cell 102.

[0186] Furthermore, when the laser weld seam is constructed as an elongated strip extending along the length direction of the ultrasonic weld (i.e., the length direction of the welding end 401), setting the length direction of the first straight groove 61 parallel to the width direction of the welding end 401 and setting the length direction of the second straight groove 62 parallel to the length direction of the welding end 401, compared to a scheme that also achieves a tooth area ratio of 50%-60%, but does not set the length direction of the first straight groove 61 parallel to the width direction of the welding end 401 and the length direction of the second straight groove 62 parallel to the length direction of the welding end 401, the two long sides of the laser weld seam profile can pass through the fluffy region 3212 less, which is beneficial to improving the problem of hot cracking in the profile of the laser weld seam and also beneficial to improving the problem of debris generation at the edge of the laser weld seam.

[0187] For example, referring to FIG14, the tooth portion 51 includes a second tooth portion 512 defined between adjacent first straight grooves 61 and adjacent second straight grooves 62. The tooth tip dimension S3 of the second tooth portion 512 in the spacing direction of the first straight grooves 61 is 1.5mm-2.4mm, and the tooth tip dimension S4 of the second tooth portion 512 in the spacing direction of the second straight grooves 62 is 1.5mm-2.4mm. Therefore, the area of ​​the second tooth portion 512 is relatively large, which is beneficial for achieving a tooth area ratio of 50%-60%, and is also beneficial for meeting the gripping force requirements to provide greater friction. Moreover, the welding head 400 has a simple structure, is easy to process, and has low manufacturing cost.

[0188] In some embodiments of this application, as shown in FIG15, the welding end 401 is elongated, 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, and the tooth area ratio of the welding end 401 is 60%-70%. For example, the tooth area ratio is 60%, 62%, 64%, 66%, 68%, 70%, etc.

[0189] For example, as shown in Figure 15, 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 straight groove 61 is parallel to the fifth direction F, and the length direction of the second straight groove 62 is parallel to the fourth direction E. The second straight groove 62 is located at the center of the welding end 401 in the fifth direction F. Thus, the multiple teeth 51 defined by the multiple first straight grooves 61 and the second straight grooves 62 can present a double-row mesh pattern.

[0190] Therefore, the welding head 400 has a simple structure and is easy to manufacture. 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 and located in the center of the width of the welding end 401. This helps reduce the proportion of the toothed grooves 6, significantly increasing the tooth area ratio of the welding end 401 to 60%-70%. This allows the contour line of the laser weld to fall more into the compaction area 3211, thus improving the problem of hot cracking in the laser weld contour over a wider area. This, in turn, improves the conductivity and connection strength between the tab 32 and the conductive part 20, enhancing the reliability of the battery cell 102. Furthermore, because the number of second straight grooves 62 is relatively small, the area of ​​the toothed portion 51 between adjacent first straight grooves 61 and second straight grooves 62 is larger, which helps increase the volume of the molten pool falling into the compaction area 3211, thereby reducing porosity in the molten pool and improving the flow capacity of the laser weld.

[0191] For example, referring to FIG15, the tooth portion 51 includes a third tooth portion 513 defined between adjacent first straight groove 61 and second straight groove 62. The tooth tip 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 tip dimension S6 of the third tooth portion 513 in the length direction of the first straight groove 61 is 3.5mm-4.5mm.

[0192] Therefore, the third tooth 513 is an elongated tooth 51 extending along the width direction of the welding end 401 in the length direction. The third tooth 513 has a large area, which is beneficial to achieving a tooth area ratio of 60%-70% and to meeting the gripping force requirements, thus providing greater friction. Moreover, the welding head 400 has a simple structure, is easy to process, and has low manufacturing cost. When the laser weld is constructed as an elongated shape extending along the length direction of the ultrasonic weld (i.e., the length direction of the welding end 401), two rows of the aforementioned elongated third teeth 513 are provided on the welding end 401. This reduces the volume of the laser weld falling in the fluffy region 3212 in the width direction of the ultrasonic weld, thereby reducing porosity in the molten pool and improving the flow capacity of the laser weld.

[0193] For example, as shown in Figure 15, the width W1 of the first straight groove 61 is smaller than the width W2 of the second straight groove 62. Thus, when the laser weld is constructed as an elongated strip extending along the length direction of the ultrasonic weld (i.e., the length direction of the welding end 401), setting the width of the first straight groove 61 to be smaller than the width of the second straight groove 62 allows the fluffy region 3212 corresponding to the first straight groove 61 to be narrower. This reduces the fluffy region 3212 traversed by the two long sides of the laser weld contour, which is beneficial for improving the problem of hot cracking in the laser weld contour. For example, as shown in Figure 15, the width W1 of the first straight groove 61 is 0.2-0.4 mm, and the width W2 of the second straight groove 62 is 0.4-0.6 mm.

[0194] In some other embodiments of this application, as shown in FIG16, the welding end 401 is elongated, and the welding tooth 5 includes a fourth tooth 514 (the shaded area in FIG16 is used to show the fourth tooth 514). The length direction of the fourth tooth 514 matches the length direction of the welding end 401, and the width direction of the fourth tooth 514 matches the width direction of the welding end 401. There are multiple fourth teeth 514, which are spaced apart along the width direction of the welding end 401.

[0195] For example, as shown in Figure 16, 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 514 is parallel to the fourth direction E, and the width direction of the fourth tooth 514 is parallel to the fifth direction F. Therefore, by setting the fourth tooth 514 as an elongated shape matching the length direction of the welding end 401, and by arranging several elongated fourth teeth 514 along the width direction of the welding end 401, it is beneficial to increase the area of ​​a single fourth tooth 514, thereby increasing the tooth area ratio of the welding end 401. This allows the contour line of the laser weld to fall more into the compaction area 3211, thus improving the problem of hot cracking in the contour of the laser weld to a greater extent, thereby improving the conductivity and connection strength of the tab 32 and the conductive part 20, and enhancing the reliability of the battery cell 102.

[0196] Furthermore, referring to Figure 17, when the laser weld (the shaded area in Figure 17 is used to show the laser weld) is constructed as an elongated strip extending along the length direction of the ultrasonic weld (i.e., the length direction of the welding end 401), by setting the fourth tooth 514 to be an elongated strip matching the length direction of the welding end 401, and by setting several elongated fourth tooth 514s arranged along the width direction of the welding end 401, the two long sides of the laser weld contour can correspond to the compaction area 3211 of the elongated strip corresponding to the fourth tooth 514, so that the two long sides of the laser weld contour can fall more into the compaction area 3211 corresponding to the fourth tooth 514, which is beneficial to improving the problem of hot cracking in the contour of the laser weld.

[0197] In some embodiments of this application, as shown in Figures 16 and 17, two fourth teeth 514 are spaced apart along the width direction of the welding end 401. The ratio of the tooth tip length S7 of the fourth teeth 514 in the length direction of the welding end 401 to the length J1 of the welding end 401 is 75%-85%, and the ratio of the tooth tip width S8 of the fourth teeth 514 in the width direction of the welding end 401 to half of the width J2 of the welding end 401 is 75%-85%. The tooth area ratio of the welding end 401 is 70%-80%. For example, the tooth area ratio is 70%, 72%, 74%, 76%, 78%, 80%, etc.

[0198] Therefore, the area of ​​each fourth tooth 514 can be further increased to increase the tooth area ratio of the welding end 401, making the tooth area ratio reach 70%-80%. This allows more of the molten pool of the laser weld to fall into the compaction area 3211, thereby reducing porosity in the molten pool and improving the flow capacity of the laser weld. Furthermore, when the laser weld is constructed as an elongated strip extending along the length of the ultrasonic weld mark, the two long sides of the laser weld contour can fall into the compaction areas 3211 corresponding to the two fourth teeth 514, which is beneficial for the laser weld setup and improves the problem of hot cracking in the laser weld contour.

[0199] In some embodiments of this application, as shown in Figures 16 and 17, each long side of the fourth tooth 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 514 is uneven, which helps to improve the gripping force during welding, so that the fourth tooth 514 can effectively compact the electrode tab 320, improve the compaction rate of the compaction area 3211 corresponding to the fourth tooth 514, and further improve the problem of hot cracking in the contour of the laser weld.

[0201] In some embodiments of this application, as shown in Figures 16 and 17, the welding tooth 5 further includes a plurality of fifth teeth 515 disposed between the two fourth teeth 514 and spaced apart along the length direction of the welding end 401. The protrusions 5141 of the two fourth teeth 514 are positioned opposite each other on one side, and two opposing protrusions 5141 are respectively disposed between each two adjacent fifth teeth 515. The contours of the fourth teeth 514 match the contours of the fifth teeth 515.

[0202] In the above technical solution, the welding end 401 can be further used to construct the welding teeth 5, thereby increasing the tooth area ratio of the welding end 401. When the two long sides of the laser weld are respectively located in the compaction area 3211 corresponding to the two fourth teeth 514, the laser weld can also cover at least part of the compaction area 3211 corresponding to multiple fifth teeth 515, which is conducive to increasing the portion of the laser weld falling in the compaction area 3211, further improving the problem of porosity in the molten pool of the laser weld, and further improving the conductivity yield of the gathering part 321 and the conductive part 20. Furthermore, since the contour of the fifth tooth 515 matches the contours of the two fourth teeth 514, that is, the protruding position of the contour of the fourth tooth 514 corresponds to the concave position of the contour of the fifth tooth 515, it is beneficial to further make full use of the space structure of the welding teeth 5 at the welding end 401, increase the area of ​​the fourth tooth 514 and the fifth tooth 515, further increase the tooth area ratio, further improve the problem of porosity in the molten pool of the laser weld, and improve the conductivity yield of the closing part 321 and the conductive part 20.

[0203] As shown in Figure 16, the tooth groove 6 includes a first partition groove 63 spaced between two fourth teeth 514 and between the fourth teeth 514 and the fifth teeth 515. Exemplarily, the tooth tip width S9 of the fifth tooth 515 in the width direction of the welding end 401 is less than 1 / 3 of the tooth tip width S8 of the fourth tooth 514 in the width direction of the welding end 401, and the groove width W3 of the first partition groove 63 is less than 2 / 3 of the tooth tip width S9 of the fifth tooth 515 in the width direction of the welding end 401. Therefore, the spacing between the two fourth teeth 514 is small, and the spacing between the fourth teeth 514 and the fifth teeth 515 is small, making the molten pool area of ​​the laser weld mostly a compacted area 3211. This helps to improve the problem of porosity in the molten pool of the laser weld and further improves the conductivity yield of the convergence portion 321 and the conductive portion 20.

[0204] In some embodiments of this application, as shown in Figures 16 and 17, the welding tooth 5 includes a plurality of sixth teeth 516, which are arranged in a plurality of spaced-apart arrangements around two fourth teeth 514, and the contours of the fourth teeth 514 match the contours of the sixth teeth 516.

[0205] In the above technical solution, by setting multiple sixth teeth 516 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 concave position of the contour of the sixth teeth 516, it helps to improve the gripping force during welding, so that the fourth teeth 514 can effectively compact the electrode tabs 320, improve the compaction rate of the compaction area 3211 corresponding to the fourth teeth 514, and further improve the problem of hot cracking in the contour of the laser weld.

[0206] As shown in Figure 16, the tooth groove 6 includes a second partition groove 64 separating the fourth tooth portion 514 and the sixth tooth portion 516 and separating two adjacent sixth tooth portions 516. Exemplarily, the groove width W4 of the second partition groove 64 can be equal to or close to the groove width W3 of the first partition groove 63.

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

[0208] In some embodiments, referring to FIG16, the sixth tooth 516 includes first sub-teeth 5161 located on both sides of the two fourth teeth 514 in the width direction of the welding end 401, and second sub-teeth 5162 located on both sides of the two fourth teeth 514 in the length direction of the welding end 401. Multiple first sub-teeth 5161 are spaced apart along the length direction of the welding end 401, and multiple second sub-teeth 5162 are spaced apart along the width direction of the welding end 401. The tooth tip width S10 of the first sub-teeth 5161 in the length direction of the welding end 401 is 1.8mm-2.2mm, and the tooth tip width S11 of the second sub-teeth 5162 in the width direction of the welding end 401 is 0.8mm-1.2mm. In the above technical solution, it is beneficial to improve the gripping force during welding, enabling the fourth teeth 514 to effectively compact the electrode tab 320.

[0209] In some embodiments, as shown in FIG12, the groove width W0 of the toothed groove 6 is 0.2mm-0.6mm, for example, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, etc. Exemplarily, the toothed groove 6 can be composed of multiple linear grooves, such as the first straight groove 61, the second straight groove 62, the first dividing groove 63, and the second dividing groove 64 mentioned above, all of which are linear grooves. The width of each linear groove can be in the range of 0.2mm-0.6mm. Therefore, the groove width of the toothed groove 6 is relatively small, thereby reducing the proportion of the toothed groove 6 on the welding end 401, increasing the proportion of the welding teeth 5, and thus increasing the proportion of the compacted area 3211 on the retracting portion 321.

[0210] In some embodiments, as shown in Figures 12 and 13, the tooth tip 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 tooth tip dimension S0 of the tooth portion 51 in the normal direction of the tooth groove 6 defining the tooth portion 51 is the tooth tip dimension S0. Exemplarily, there are multiple teeth 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, and the tooth tip 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. Therefore, the area of ​​a single tooth portion 51 is not too small, which is beneficial for improving the compaction rate of the compaction zone 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 projected distance E between the tooth tip and the tooth root of the tooth portion 51 is 0.1 mm to 0.2 mm.

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

[0213] Therefore, by setting the tooth height H of the tooth 51 to be less than or equal to 2.5 mm, and the projected distance E between the tooth tip and the tooth root of the tooth 51 to be 0.1 mm-0.2 mm, the side of the tooth 51 has a certain inclination, which is convenient to improve the compaction rate and reduce the edge sharpness of the tooth 51 to improve the problem of scratching the electrode tab 320.

[0214] In some embodiments, as shown in Figure 12, the edge of the welding end 401 is rounded, and the rounding radius R is 0.5mm-2mm, such as 0.5mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 2mm, etc. Therefore, during ultrasonic welding, the problem of the edge of the welding end 401 scratching the edge of the tab 320 can be mitigated, facilitating smooth welding and improving the connection reliability and conductivity between the tab 32 and the conductive part 20. Furthermore, a larger rounding radius R is beneficial for effective welding without damaging the foil under high welding parameters, thus mitigating the cracking problem of the tab 320.

[0215] In related technologies, ultrasonic welding heads typically employ uniform welding teeth, with the tooth area at the welding end accounting for less than 40%. When welding the tabs with this ultrasonic welding head, the compacted and loose areas in the resulting ultrasonic weld are basically evenly distributed, with the compacted area accounting for less than 40% and the compaction rate of the compacted area being less than 5%. When laser welding is used to weld this ultrasonic weld to the electrode component, the outline of the laser weld will mostly fall in the loose area. Since the multiple tabs in the loose area are not fused together, there are interlayer gaps. These gaps will cause thermal cracks in the outline of the laser weld, affecting the connection reliability and conductivity yield between the tabs and the conductive parts, reducing the current carrying capacity of the battery cell, and affecting the reliability of the battery cell.

[0216] In the embodiments of this application, by improving the distribution, shape, and size of the welding teeth 5 of the welding end 401 of the welding head 400, the processed ultrasonic weld can provide a larger compaction area 3211 and improve the compaction rate of the compaction area 3211. Moreover, it can provide a tight compaction area 3211 along the direction of laser welding between the tab 32 and the conductive part 20 (e.g., along the length direction of the welding end 401), thereby effectively improving the problem of hot cracking in the contour of the laser weld, improving the connection reliability and conductivity yield between the tab 32 and the conductive part 20, and improving the reliability of the battery cell 102.

[0217] Furthermore, welding parameters and tooth arrangement can be adjusted according to different welding methods. For example, when welding with the welding head 400 of this application embodiment, it can vibrate along the length direction of the welding end 401 or along the width direction of the welding end 402. For example, the entire welding head 400 can be magnified or reduced by 20%-60% depending on the vibration direction. Therefore, the welding head 400 of this application embodiment has a wide range of applications.

[0218] Referring to Figures 18 and 19, an embodiment of this application also proposes an ultrasonic welding device 2000, including: a welding head 400, a welding seat 500, and a drive cylinder 600. The drive cylinder 600 is located on the side of the welding head 400 away from the welding seat 500, and the drive cylinder 600 is used to drive the welding head 400 to move toward the welding seat 500. The welding head 400 is the welding head 400 of any of the above-described embodiments.

[0219] For example, the drive cylinder 600 is located directly above the ultrasonic welding device 2000. The welding head 400 is connected below the drive cylinder 600 via guide rails, conversion blocks, etc. The drive cylinder 600, welding head 400, and welding base 500 are arranged sequentially from top to bottom in a straight line, making the ultrasonic welding process more stable, reducing mechanical wear, and minimizing the deformation of the welding head 400. During welding, the multilayer electrode tabs 320 to be welded can be placed between the welding head 400 and the welding base 500. The drive cylinder 600 operates, pushing the welding head 400 downwards towards the welding base 500. The welding head 400 and the welding base 500 weld the multilayer electrode tabs 320 together, forming an ultrasonic weld mark.

[0220] Since the welding head 400 according to the embodiment of this application is advantageous in increasing the area of ​​the compacted region 3211 in the ultrasonic weld, the ultrasonic weld welded by the ultrasonic welding device 2000 has a larger compacted region 3211, which is beneficial to improving the subsequent laser welding effect between the tab 32 and the conductive part 20.

[0221] In the embodiments of this application, the type of drive cylinder 600 is not limited, such as an electric cylinder, hydraulic cylinder, pneumatic cylinder, etc. By increasing the pressure of the drive cylinder 600, the compaction rate of the compaction zone 3211 can be increased. For example, in some embodiments, the drive cylinder 600 is a pneumatic cylinder with a diameter greater than 125 mm.

[0222] In the embodiments of this application, the thickness T1 of the compacted region 3211 is less than the theoretical thickness T2 of the tab 32, resulting in a compaction rate of the compacted region 3211 greater than 0%. This indicates 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 apparatus 2000 of this application embodiment, the surface pressure provided by the welding head 400 is greater than the yield strength of the tab 320, such as aluminum foil.

[0223] For example, under ultrasonic conditions, the yield strength Rp0.2 of the electrode tab 320, such as aluminum foil, is σ; the length of the welding end 401 of the welding head 400 is J1; the width of the welding end 401 is J2; the area of ​​the welding end 401 of the welding head 400 is S = J1 × J2; when the drive 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, when Pπ(d / 2) 2 When / S≥σ, the tab 320 can be compressed and yielded and undergo plastic deformation, so that the compaction rate of the compacted region 3211 can be greater than 0%.

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

[0225] By increasing the cylinder diameter to greater than 125mm, the surface pressure provided by the welding head 400 can be increased, thereby achieving the interlayer gap of the electrode tabs 320, increasing the compaction rate of the compaction zone 3211, creating favorable conditions for subsequent laser welding, and improving the problem of hot cracking in the profile of the laser weld.

[0226] In related technologies, ultrasonic welding machines cannot form effective interlayer bonding after ultrasonic welding of the tabs. There are gaps between the multiple tabs, and the gaps are large and the compaction rate is low. During the cooling stage after laser welding of the ultrasonic weld and the conductive part, the contour of the laser weld seam forms hot cracks, which affects the performance of the battery cell.

[0227] The ultrasonic welding device 2000 in this embodiment can be a direct-pressure welding machine with stronger welding capabilities. By increasing the diameter of the cylinder, it can provide ultra-high pressure to the tab 320 during ultrasonic pre-welding. Under this pressure, the frictional heat generated by ultrasonic pre-welding is more likely to soften the aluminum foil, thereby forming a tighter interlayer bond. This can form an effective interlayer weld of the tab 320, and the tab undergoes significant plastic deformation, achieving a solid welding effect between multiple tabs 320, reducing the interlayer gap, and increasing the compaction rate of the compaction area 3211. When laser welding the ultrasonic weld mark and the conductive part 20, the outline of the laser weld is less prone to hot cracking, thereby improving the problem of hot cracking in the outline of the laser weld, improving the conductivity and connection strength of the tab 32 and the conductive part 20, reducing porosity in the molten pool of the laser weld, improving the current carrying capacity of the laser weld, and enhancing the reliability of the battery cell 102.

[0228] The ultrasonic welding apparatus 2000 of this application, by developing an ultra-large diameter cylinder and optimizing the welding teeth 5 of the welding head 400, enables the electrode tabs 320 to undergo plastic deformation under ultra-high pressure, reducing the interlayer gap between the electrode tabs 320. Furthermore, the optimized welding teeth 5 provide a larger compaction area, which is beneficial for increasing the area of ​​the compacted region 3211 in the ultrasonic weld, thereby providing a good foundation for subsequent laser welding of the electrode tabs 32 and the conductive part 20, and improving the problem of hot cracking in the contour of the laser weld. This optimization method is simple, highly reliable, and a simple and reliable effective method to improve the hot cracking of laser welding after ultrasonic pre-welding, without requiring other process designs or the addition of mechanical components to solve this technical problem.

[0229] For example, the cylinder diameter is 160mm or 200mm. Therefore, the cylinder is easier to manufacture and can function, and the compaction rate of the compaction area 3211 is high, which can effectively improve the problem of hot cracking in the contour of the laser weld, improve the conductivity and connection strength between the tab 32 and the conductive part 20, reduce porosity in the molten pool of the laser weld, improve the current carrying capacity of the laser weld, and enhance the reliability of the battery cell 102.

[0230] Referring to Figures 2-7, an embodiment of this application also proposes a battery cell 102, including: a housing component 1, a terminal component 2, and an electrode assembly 3. The terminal component 2 is disposed on 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 pieces 320 stacked together. The plurality of tab pieces 320 are connected to form a gathering portion 321. The gathering portion 321 is processed by an ultrasonic welding device 2000 of any of the above schemes and a compacted area 3211 is processed by welding teeth 5. The gathering portion 321 is stacked with the conductive portion 20 and connected to form a connecting portion 4. The gathering portion 321 includes a compacted area 3211. The thickness of the compacted area 3211 is less than the stacking thickness of the plurality of tab pieces 320 in the tab portion 32. The connecting portion 4 includes a first portion 41 formed in the gathering portion 321. At least a majority of the outline of the first portion 41 is located in the compacted area 3211.

[0231] In the above technical solution, since at least a portion of the outline of the portion of the connecting part 4 formed on the gathering part 321 is disposed in the compaction region 3211, the multilayer tabs 320 in the compaction region 3211 are very tightly bonded together, which helps to improve the problem of thermal cracking in the outline of the connecting part 4, improves the conductivity and connection strength between the tab 32 and the conductive part 20, and enhances the overcurrent capacity and reliability of the battery cell 102.

[0232] In some embodiments, at least a majority of the outline of the first portion 41 is located within the compacted region 3211. That is, at least a majority of the outline of the portion of the connecting portion 4 formed on the gathered portion 321 is located within the compacted region 3211. This means that more than 50% (including 50%) of the outline of the portion of the connecting portion 4 formed on the gathered portion 321 is located within the compacted region 3211. In other words, the proportion of the outline of the first portion 41 falling within the compacted region 3211 is greater than the proportion falling within the fluffy region 3212. This can significantly improve the problem of thermal cracking in the laser weld outline, further improve the conductivity and connection strength between the tab portion 32 and the conductive portion 20, and enhance the reliability of the battery cell 102.

[0233] In some embodiments, referring to Figures 7 and 17, the connecting portion 4 extends from the outer surface of the closing portion 321 toward the conductive portion 20, and the first portion 41 includes a surface portion 411 formed on the outer surface of the closing portion 321, and more than 60% of the outline 4x of the surface portion 411 falls on the compacted region 3211.

[0234] In the above technical solution, by setting the extension direction of the connecting part 4 to be from the closing part 321 to the conductive part 20, it is convenient for the welding head 400 to be aligned with the closing part 321. 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 closing part 321, and accurately weld along the welding trajectory, so that at least most of the outline of the part of the connecting part 4 formed on the closing part 321 can be reliably located in the compacted area 3211, thereby effectively improving the conductivity and connection strength of the tab part 32 and the conductive part 20, and improving the overcurrent capacity and reliability of the battery cell 102.

[0235] Furthermore, by ensuring that more than 60% of the outline 4x of the surface portion 411 falls within the compacted region 3211, the problem of hot cracking in the weld outline of the connecting portion 4 on the surface of the closing portion 321 can be further improved. In addition, since the connecting portion 4 extends from the outer surface of the closing portion 321 towards the conductive portion 20, the outline 4y of the inner portion 412 can extend from the outline 4x of the surface portion 411 towards the conductive portion 20. When more than 60% of the outline 4x of the surface portion 411 falls within the compacted region 3211, it is beneficial to further increase the proportion of the outline 4y of the inner portion 412 falling within the compacted region 3211 relative to falling within the loose region 3212, thereby further improving the overall problem of hot cracking in the outline of the first portion 41 of the connecting portion 4 formed on the closing portion 321.

[0236] In some embodiments, the compaction rate of the compaction region 3211 is greater than or equal to 12%. Thus, by setting the compaction rate of the compaction region 3211 to be greater than or equal to 12%, there are almost no gaps in the compaction region 3211. The portion of the connecting part 4 falling into the compaction region 3211 is less prone to thermal cracks and pores, thereby improving the overall 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 gathering part 321.

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

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

[0239] Experiment 1 obtained the ultrasonic pre-welding effect and laser welding effect of Comparative Example 1. Figure 20 shows the local cross-sectional morphology of the converging 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 converging part and the conductive part after laser welding. It can be seen from the figure that the outline of the laser weld has thermal cracks, and the proportion of thermal cracks is close to 100%.

[0240] Experiment 2 obtained the ultrasonic pre-welding effect and laser welding effect of Comparative Example 2. Figure 22 shows the local cross-sectional morphology of the converging 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 converging part and the conductive part after laser welding. It can be seen from the figure that the outline of the laser weld has thermal cracks, and the proportion of thermal cracks is close to 70%.

[0241] Experiment 3 obtained the ultrasonic pre-welding effect and laser welding effect of Comparative Example 3. Figure 24 shows the local cross-sectional morphology of the converging 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 converging part and the conductive part after laser welding. It can be seen from the figure that the outline of the laser weld has hot cracks, and the proportion of hot cracks is close to 40%.

[0242] 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 converging part of Example 1. It can be seen that the thickness T1 of the compacted area is 609 μm, and the compaction rate is calculated to be 6.3%. Figure 27 shows the local cross-sectional morphology of the converging part and the conductive part after laser welding. It can be seen from the figure that a small number of hot cracks appear in the outline of the laser weld, and the proportion of hot cracks is close to 15%.

[0243] 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 converging part of Example 2. It can be seen that the thickness T1 of the compacted area is 564μm, and the calculated compaction rate is 13.2%. Figure 29 shows the local cross-sectional morphology of the converging part and the conductive part after laser welding. It can be seen from the figure that the outline of the laser weld is almost free of thermal cracks.

[0244] 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 converging 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 converging part and the conductive part after laser welding. It can be seen from the figure that the outline of the laser weld has no thermal cracks.

[0245] Experiment 7: The ultrasonic pre-welding effect and laser welding effect of Example 4 were obtained. Figure 32 shows the local cross-sectional morphology of the converging part of Example 4. It can be seen that the thickness T1 of the compacted area is 362 μm, and the calculated compaction rate is 44.3%. Figure 33 shows the local cross-sectional morphology of the converging part and the conductive part after laser welding. It can be seen from the figure that there are no hot cracks 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 hot cracking in the profile of laser weld can be significantly improved, and when the compaction rate exceeds 12%, the profile of laser weld can be basically free of hot cracks.

[0247] This application also provides a battery 100, including a battery cell 102 of any of the above-described embodiments. Since the reliability of the battery cell 102 according to the embodiments of this application is improved, the reliability of the battery 100 is thus enhanced. It is worth noting that the battery 100 according to the embodiments of this application may or may not include a casing 101.

[0248] For example, the battery 100 also includes a busbar component, and multiple battery cells 102, at least two of which are electrically connected through the busbar component. This allows for the series and / or parallel connection of multiple battery cells 102. For instance, 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 one busbar component, while the cathode of that 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 electrode body 21 in the electrode component 2 to achieve electrical connection between the battery cell 102 and the busbar component.

[0249] This application also provides an electrical device including a battery 100 from any of the above-described embodiments. The battery 100 provides electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems using the battery 100. Because the reliability of the battery 100 is improved, it is beneficial to improve the power consumption performance of the electrical device.

[0250] Hereinafter, with reference to FIG13, a welding head 400 according to a specific embodiment of the present application will be described.

[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. There are multiple first straight grooves 61 arranged in parallel, and multiple second straight grooves 62 arranged in parallel. The welding end 401 is elongated. 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 to 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 arranged intersectingly to define multiple rhomboid first teeth 511. The welding end 401 presents a rhomboid mesh overall.

[0252] The tooth tip dimension S1 of the first tooth 511 in the direction of interval between adjacent first straight grooves 61 is 1.6mm-2mm, and the tooth tip dimension S2 of the first tooth 511 in the direction of interval between adjacent second straight grooves 62 is 1.6mm-2mm. The groove width W1 of the first straight groove 61 is 0.2mm-0.3mm, the groove width W2 of the second straight groove 62 is 0.2mm-0.3mm, the tooth height of the first tooth 511 is 0.2mm, and the projected distance between the tooth tip and the tooth root of the first tooth 511 is 0.1mm-0.2mm. The edge of the welding end 401 is rounded with a rounding radius of 1mm. The length of the welding end 401 is 24mm, the width is 14mm, and the tooth area ratio of the welding end 401 is 40%-50%.

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

[0254] Hereinafter, with reference to FIG14, a welding head 400 according to a specific embodiment of the present application will be described.

[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. There are multiple first straight grooves 61 arranged in parallel, and multiple second straight grooves 62 arranged in parallel. The welding end 401 is elongated. 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 intersected to define multiple rectangular second teeth 512. The welding end 401 presents a grid pattern as a whole.

[0256] The tooth tip dimension S3 of the second tooth 512 in the spacing direction of the first straight groove 61 is 1.5mm-2.4mm, and the tooth tip dimension S4 of the second tooth 512 in the spacing direction of the second straight groove 62 is 1.5mm-2.4mm. 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 0.2mm-0.4mm, the tooth height of the second tooth 512 is 0.2mm, and the projected distance between the tooth tip and the tooth root of the second tooth 512 is 0.1mm-0.2mm. The edge of the welding end 401 is rounded with a rounding radius of 1mm. The length of the welding end 401 is 24mm, the width is 14mm, and the tooth area ratio of the welding end 401 is 50%-60%.

[0257] The morphology and cross-section of the ultrasonic weld mark processed by the welding head 400 are shown in Figures 36-37. The area ratio of the compacted region 3211 to the welding end 401 is 50%-60%, and there are almost no interlayer gaps in the compacted region 3211.

[0258] Hereinafter, with reference to FIG15, a welding head 400 according to a specific embodiment of the present application will be described.

[0259] The welding end 401 of the welding head 400 is divided into welding teeth 5 by the first straight groove 61 and the second straight groove 62. The welding end 401 is elongated. There are multiple first straight grooves 61 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 intersects with multiple first straight grooves 61 to define multiple elongated third teeth 513. The welding end 401 presents a double-row elongated grid shape.

[0260] The tooth tip dimension S5 of the third tooth 513 in the spacing direction of the first straight groove 61 is 2mm-2.4mm, the tooth tip dimension S6 of the third tooth 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 513 is 0.2mm, the projected distance between the tooth tip and the tooth root of the third tooth 513 is 0.1mm-0.2mm, the edge of the welding end 401 is rounded with a rounding radius of 1.5mm, the length of the welding end 401 is 25mm, the width is 13.5mm, and the tooth area ratio of the welding end 401 is 60%-70%.

[0261] The morphology and cross-section of the ultrasonic weld mark processed by the welding head 400 are shown in Figures 38-39. The area ratio of the compacted region 3211 to the welding end 401 is 60%-70%, and there are almost no interlayer gaps in the compacted region.

[0262] Hereinafter, with reference to FIG16, 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 sections 514, multiple fifth tooth sections 515, and multiple sixth tooth sections 516 through the tooth groove 6. The contour of the fourth tooth section 514 matches the contour of the fifth tooth section 515, and the contour of the fourth tooth section 514 matches the contour of the sixth tooth section 516. The welding end 401 is elongated. The length direction of the fourth tooth 514 matches the length direction of the welding end 401, and the width direction of the fourth tooth 514 matches the width direction of the welding end 401. Two fourth teeth 514 are spaced apart along the width direction of the welding end 401. Each long side of the fourth tooth 514 has multiple 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. Multiple fifth teeth 515 are located between the two fourth teeth 514 and are spaced apart along the length direction of the welding end 401. The protrusions 5141 on the side of the two fourth teeth 514 are positioned opposite each other, so that two opposing protrusions 5141 are provided between each pair of adjacent fifth teeth 515. Multiple sixth teeth 516 are spaced apart around the two fourth teeth 514.

[0264] The sixth tooth 516 includes a first sub-tooth 5161 located on both sides of the two fourth tooth 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 514 in the length direction of the welding end 401. There are multiple first sub-tooths 5161 and they are spaced apart along the length direction of the welding end 401. There are multiple second sub-tooths 5162 and they are spaced apart along the width direction of the welding end 401. The tooth tip 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 tip 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 of 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 the tooth root 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 length of the welding end 401 is 25mm, the width is 14mm, and the tooth area ratio of the welding end 401 is 70%-80%.

[0266] The morphology and cross-section of the ultrasonic weld mark processed by the welding head 400 are shown in Figures 40-41. The area ratio of the compacted region 3211 to the welding end 401 is 70%-80%, and there are almost no interlayer gaps in the compacted region 3211.

[0267] In this embodiment, the use of a large-diameter cylinder, combined with a welding head having two large, elongated teeth, can effectively increase the area ratio of the compaction area 3211 relative to the welding end 401. Furthermore, multiple small teeth are provided between and around the two large, elongated teeth to provide welding gripping force, which firmly grips the foil during welding and provides greater friction.

[0268] Furthermore, the embodiments of this application are also applicable to batteries for 3C products, such as small batteries used in mobile phones and other devices. 3C product batteries have fewer tab layers and narrower tab widths. The welding head can be a flat-headed electro-spark etching head for roughening, or a welding head with a low tooth height (e.g., tooth height ≤ 0.1mm). For example, power batteries typically have 30-120 tab layers, with a tab thickness of 13μm-15μm and a tooth height of 0.1mm-0.4mm; while 3C product batteries typically have 10-50 tab layers, with a tab thickness of 6μm-10μm, an ultrasonic welding width of approximately 5mm, and a tooth height of less than 0.1mm. Laser welding can be performed using a high-frequency pulsed laser or a low-power continuous laser, ensuring that 60% to 100% of the laser weld contour falls within the compacted area to improve battery reliability.

[0269] In the production of battery cells, ultrasonic welding can be used to pre-weld multiple tabs in the electrode area to form an ultrasonic weld mark. Then, laser welding is used to weld the ultrasonic weld mark to the conductive part of the terminal component, realizing the connection and electrical conduction between the electrode assembly and the terminal component. However, in related technologies, the ultrasonic welding machine used for ultrasonic welding cannot form an effective interlayer weld after pre-welding the tabs. There are gaps between the multiple tabs. The existence of these gaps will increase the porosity in the molten pool of the laser weld, reducing the current carrying capacity of the battery cell. Furthermore, during the cooling stage after laser welding, the profile of the laser weld will develop thermal cracks, which will worsen the problem and affect the connection reliability and conductivity yield between the tabs and the conductive part, thus affecting the performance of the battery cell.

[0270] The ultrasonic welding apparatus provided in this application embodiment 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, in conjunction with the welding tooth design of the welding head, increase the area of ​​the compaction region and optimize the distribution of the compaction region. This helps to improve the problem of thermal cracking deterioration in the contour of the laser weld and reduce the proportion of pores in the laser weld pool. This improves the connection reliability and conductivity yield between the tab and the conductive part, enhances the current carrying capacity of the battery cell, and improves the performance of the battery cell.

[0271] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0272] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A welding tip, 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 by the tooth grooves, and a tooth area ratio of the welding end is greater than or equal to 40%.

2. The welding tip of claim 1, wherein, The tooth grooves include first straight grooves and second straight grooves arranged in a cross manner, the first straight grooves are a plurality of and arranged in parallel, the tooth portions are defined between adjacent first straight grooves and second straight grooves, and groove widths of the first straight grooves and the second straight grooves are both less than a spacing between adjacent first straight grooves.

3. The welding tip of claim 2, wherein, The spacing between adjacent first straight grooves is 1.5 mm-2.5 mm.

4. The welding tip of claim 2, wherein, The second straight grooves are a plurality of and arranged in parallel, the tooth portions are defined between adjacent first straight grooves and adjacent second straight grooves, and groove widths of the first straight grooves and the second straight grooves are both less than a spacing between adjacent second straight grooves.

5. The welding tip of claim 4, wherein, The spacing between adjacent second straight grooves is 1.5 mm-2.5 mm.

6. The welding tip of claim 4, wherein, The welding end is in a strip shape, a length direction of the first straight grooves intersects a length direction of the welding end at an acute angle, a length direction of the second straight grooves is symmetrical to the length direction of the first straight grooves about a width direction axis of the welding end, and the tooth area ratio is 40%-50%.

7. The welding tip of claim 6, wherein, The length direction of the first straight grooves intersects the length direction of the welding end at 45°, the tooth portions include first tooth portions defined between adjacent first straight grooves and adjacent second straight grooves, a tooth top size of the first tooth portions in a spacing direction of the adjacent first straight grooves is 1.6 mm-2 mm, and a tooth top size of the first tooth portions in a spacing direction of the adjacent second straight grooves is 1.6 mm-2 mm.

8. The welding tip of claim 4, wherein, The welding end is in a strip shape, a length direction of the first straight grooves is parallel to a width direction of the welding end, a length direction of the second straight grooves is parallel to a length direction of the welding end, and the tooth area ratio is 50%-60%.

9. The welding tip of claim 8, wherein, The tooth portions include second tooth portions defined between adjacent first straight grooves and adjacent second straight grooves, a tooth top size of the second tooth portions in the spacing direction of the first straight grooves is 1.5 mm-2.4 mm, and a tooth top size of the second tooth portions in the spacing direction of the second straight grooves is 1.5 mm-2.4 mm.

10. The welding tip of claim 2, wherein, The welding end is in a strip shape, a length direction of the first straight groves is parallel to a width direction of the welding end, a length direction of the second straight groves is parallel to a length direction of the welding end and located at a width center of the welding end, and the tooth area ratio is 60%-70%.

11. The welding tip of claim 10, wherein, The tooth portions include third tooth portions defined between adjacent first straight grooves and second straight grooves, a tooth top size of the third tooth portions in the spacing direction of the first straight grooves is 2 mm-2.4 mm, and a tooth top size of the third tooth portions in a length direction of the first straight grooves is 3.5 mm-4.5 mm.

12. The welding tip of claim 10, wherein, The groove width of the first straight grooves is less than the groove width of the second straight grooves.

13. The welding tip of claim 1, wherein, The welding end is elongated, and the welding tooth includes a fourth tooth. The length direction of the fourth tooth matches the length direction of the welding end, and the width direction of the fourth tooth matches the width direction of the welding end. There are multiple fourth teeth, which are spaced apart along the width direction of the welding end.

14. The welding tip of claim 13, wherein, The fourth tooth consists of two teeth spaced apart along the width direction of the welding end. The ratio of the tooth tip length of the fourth tooth in the length direction of the welding end to the length of the welding end is 75%-85%, the ratio of the tooth tip width of the fourth tooth in the width direction of the welding end to half the width of the welding end is 75%-85%, and the tooth area accounts for 70%-80%.

15. The welding tip of claim 14, wherein, Each long side of the fourth tooth has a plurality of protrusions spaced apart along the length direction of the welding end, the protrusions protruding toward the width direction of the welding end.

16. The welding tip of claim 15, wherein, The welding tooth also includes a plurality of fifth teeth disposed between the two fourth teeth and spaced apart along the length direction of the welding end. The protrusions of the two fourth teeth are positioned opposite each other on one side, and two opposite protrusions are respectively disposed between each two adjacent fifth teeth. The contour lines of the fourth teeth match the contour lines of the fifth teeth.

17. The welding tip of claim 15, wherein, The welding tooth includes a plurality of sixth teeth, which are arranged around the two fourth teeth at intervals, and the outline of the fourth teeth matches the outline of the sixth teeth.

18. The welding tip of claim 15, wherein, The protrusion has a length of 1.5mm-2.4mm along the length of the weld end and a width of 0.2mm-1.2mm along the width of the weld end.

19. The welding tip of any one of claims 1-18, wherein, The groove width is 0.2mm-0.6mm.

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

21. The welding tip of any one of claims 1-20, wherein, The tooth height of the tooth is less than or equal to 2.5 mm, and the projected distance between the tooth tip and the tooth root is 0.1 mm to 0.2 mm.

22. The welding tip of any one of claims 1-21, wherein, The edges of the welded end are rounded, and the radius of the rounded corner is 0.5mm-2mm.

23. An ultrasonic welding device, wherein, include: The drive cylinder, the welding socket, and the welding head according to any one of claims 1-22, wherein the drive cylinder is located on the side of the welding head away from the welding socket and is used to drive the welding head to move toward the welding socket.

24. The ultrasonic welding device of claim 23, wherein, The drive cylinder is a pneumatic cylinder with a diameter greater than 125 mm.

25. The ultrasonic welding device of claim 24, wherein, The cylinder has a diameter of 160mm or 200mm.

26. A battery cell, wherein, include: Housing components; An electrode component is disposed on the housing component, and the electrode component includes a conductive portion; An electrode assembly is housed in the housing component and includes an electrode tab portion. The electrode tab portion includes a plurality of stacked electrode tabs. The plurality of electrode tabs are connected to form a folded portion. The folded portion is stacked with and connected to the conductive portion to form a connecting portion. The gathering portion includes a compacted area, the thickness of which is less than the stacked thickness of the plurality of electrode tabs in the electrode tab portion. The connecting portion includes a first portion formed in the gathering portion, at least a majority of the outline of the first portion being located in the compacted area. The gathering portion is processed using an ultrasonic welding apparatus according to any one of claims 23-25 ​​and the compacted area is processed by the welding teeth.

27. The battery cell of claim 26, wherein, The connecting portion extends from the outer surface of the gathering portion toward the conductive portion, and the first portion includes a surface portion formed on the outer surface of the gathering portion, with more than 60% of the outline of the surface portion falling within the compaction area.

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

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

30. A battery, wherein, Includes the battery cell according to any one of claims 26-29.

31. An electrical device, comprising: Includes the battery according to claim 30.

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