Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device, which belong to the technical field of batteries. The battery cell comprises: a housing component, a terminal component, and an electrode assembly, wherein the terminal component comprises a conductive part; and the electrode assembly is accommodated in the housing component and comprises a tab part, the tab part comprises a plurality of stacked tab pieces, the plurality of tab pieces are connected to form a gathered part, the gathered part and the conductive part are stacked and connected to form a connection part, the gathered part comprises a compacted area, the connection part comprises a first portion formed on the gathered part, and at least most of the contour line of the first portion is located in the compacted area.

Description

Battery cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202410405344.4 and application date 2024-04-03, and claims the priority of the above-mentioned Chinese patent application. The entire content of the above-mentioned Chinese patent application is hereby introduced into this application as a reference. Technical Field

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

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

[0005] Summary of the Invention

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

[0007] In a first aspect, an embodiment of the present application provides a battery cell, comprising: a shell component, a pole component and an electrode assembly, the pole component being arranged in the shell component, the pole component including a conductive portion, the electrode assembly being accommodated in the shell component and including a pole ear portion, the pole ear portion including a plurality of pole ear sheets arranged in a stacked manner, the plurality of pole ear sheets being connected to form a gathered portion, the gathered portion being overlapped with the conductive portion and connected to form a connecting portion, the gathered portion including a compacted area, the thickness of the compacted area being less than the stacking thickness of the plurality of pole ear sheets in the pole ear portion, the connecting portion including a first portion formed in the gathered portion, at least most of the contour line of the first portion being located in the compacted area.

[0008] In the above technical solution, since at least most of the contour lines of the portion of the connection formed on the gathered portion are arranged in the compacted area, the multiple layers of the pole tabs in the compacted area are very tightly combined together, which is beneficial to improving the problem of thermal cracks in the contour of the connection portion, improving the conductive yield and connection strength between the pole tab portion and the conductive portion, and enhancing the current carrying capacity and reliability of the battery cell.

[0009] In some embodiments, the connecting portion extends from an outer surface of the gathered portion toward the conductive portion, and the first portion includes a surface portion formed on the outer surface of the gathered portion.

[0010] In the above technical solution, by setting the extension direction of the connecting portion to be from the gathered portion to the conductive portion, it is convenient to align the welding head with the gathered portion, so that the welding head can reasonably design the welding trajectory according to the distribution of the compacted area and the fluffy area on the gathered portion, and accurately weld along the welding trajectory, so that at least most of the contour line of the part of the connecting portion formed on the gathered portion can be reliably located in the compacted area, thereby effectively improving the conductivity yield and connection strength between the pole ear portion and the conductive portion, and improving the current carrying capacity and reliability of the battery cell.

[0011] In some embodiments, at least a majority of the area of ​​the surface portion falls within the compacted region.

[0012] In the above technical solution, since the connecting portion extends from the outer surface of the gathered portion toward the conductive portion, the internal portion can extend from the surface portion toward the conductive portion. When at least most of the area of ​​the surface portion falls in the compacted area, it is beneficial to increase the volume of the internal portion falling in the compacted area. Since there is almost no interlayer gap between the multi-layer tab sheets in the compacted area, it is not easy for pores caused by interlayer gaps to appear in the molten pool in the compacted area, which is beneficial to reduce the pores formed in the internal portion, thereby improving the flow capacity of the connecting portion.

[0013] In some embodiments, at least a majority of the contour of the surface portion falls within the compacted region.

[0014] In the above technical solution, by ensuring that at least a majority of the contour of the surface portion falls within the compacted area, the problem of thermal cracking in the weld profile of the connecting portion on the surface of the gathered portion can be effectively alleviated. Furthermore, because the connecting portion extends from the outer surface of the gathered portion toward the conductive portion, the contour of the inner portion can extend from the contour of the surface portion toward the conductive portion. When at least a majority of the contour of the surface portion falls within the compacted area, the proportion of the contour of the inner portion falling within the compacted area relative to the contour of the fluffy area is increased, thereby overall alleviating the problem of thermal cracking in the contour of the connecting portion formed in the first portion of the gathered portion.

[0015] In some embodiments, more than 60% of the contour of the surface portion falls within the compacted region.

[0016] In the above technical solution, by ensuring that at least 60% of the surface portion's contour falls within the compacted region, the problem of thermal cracking in the weld profile of the connecting portion on the surface of the gathered portion can be further alleviated. Furthermore, because the connecting portion extends from the outer surface of the gathered portion toward the conductive portion, the contour of the inner portion can extend from the surface portion's contour toward the conductive portion. When at least 60% of the surface portion's contour falls within the compacted region, the proportion of the inner portion's contour falling within the compacted region relative to the proportion falling within the bulky region can be further increased, thereby further improving the overall problem of thermal cracking in the contour of the connecting portion formed in the first portion of the gathered portion.

[0017] In some embodiments, the surface of the gathered portion is elongated, the surface portion is elongated and matches the length direction of the gathered portion, and at least most of each of the two long sides of the surface portion is located in the compacted area.

[0018] In the above technical solution, the surface part can make full use of the space of the gathered part, increase the area of ​​the surface part, and improve the current flow capacity. Moreover, by setting at least most of each long side to be located in the compacted area, it is beneficial to increase the part of the contour line of the surface part falling in the compacted area, improve the contour thermal crack problem of the surface part, improve the conductivity yield and connection strength of the gathered part and the conductive part, and thus improve the reliability of the battery cell.

[0019] In some embodiments, the compacted area includes a first sub-area, which is long and narrow and matches the length and width directions of the gathered portion respectively. The length of the first sub-area exceeds half of the length of the gathered portion. There are two first sub-areas and they are spaced apart along the width direction of the gathered portion. The two long sides of the surface portion correspond to the two first sub-areas respectively.

[0020] In the above technical solution, by configuring the compacted region to include the two first subregions, and positioning the two long sides of the surface portion of the connection portion within the two first subregions, the length of the first subregions is increased, and the majority of the surface portion's contour line can fully utilize the compacted region. This further increases the portion of the surface portion's contour line that falls within the compacted region, thereby further alleviating the risk of thermal cracking within the surface portion's contour, further improving the conductivity yield and connection strength between the gathered portion and the conductive portion, and thereby enhancing the reliability of the battery cell. Furthermore, as the inner portion extends from the surface portion toward the conductive portion, the majority of the inner portion can also fall within the first subregion, thereby increasing the volume of the inner portion within the compacted region, further alleviating the risk of air holes within the inner portion, and further improving the current carrying capacity.

[0021] In some embodiments, each long side of the first sub-region has a plurality of protruding segments spaced apart along the length direction of the gathered portion, and the protruding segments protrude toward the width direction of the gathered portion.

[0022] In the above technical solution, each long side of the first sub-area is uneven, which helps to improve the grip during welding and provide greater friction, so that the first sub-area can be effectively compacted and the compaction rate of the first sub-area is improved. In this way, when part of the contour line of the laser weld falls more on the first sub-area, the problem of thermal cracks in this part of the contour line can be further improved.

[0023] In some embodiments, the compaction area includes a plurality of second sub-areas arranged between two first sub-areas and spaced apart along the length direction of the converged portion. The protruding segments of the two first sub-areas close to each other on one side are positioned opposite to each other, and two opposite protruding segments are respectively arranged between each two adjacent second sub-areas.

[0024] In the above technical solution, the space of the converged portion can be further utilized to construct a compaction area. When the two long sides of the surface portion correspond to the two first sub-areas respectively, the surface portion can cover at least part of the second sub-area, which is conducive to increasing the portion of the laser weld falling in the compaction area, further improving the problem of pores in the molten pool of the laser weld, and further improving the flow capacity.

[0025] In some embodiments, the gathering portion includes a fluffy area, the fluffy area includes a first fluffy area arranged between two first sub-areas, and separated between the two first sub-areas and between the first sub-area and the second sub-area, and the first fluffy area is in the form of a line on the outer surface of the gathering portion so that the outline of the second sub-area matches the outline of the first sub-area.

[0026] In the above technical solution, a first fluffy area in the form of a line is set to separate the two first sub-areas, and to separate the first sub-area from the second sub-area, so that the outline of the second sub-area matches the outline of the two first sub-areas, that is, the protruding position of the outline of the first sub-area corresponds to the recessed position of the outline of the second sub-area, the distance between the two first sub-areas is small, and the distance between the first sub-area and the second sub-area is small, so that most of the area where the molten pool of the laser weld is located is a compacted area, which is beneficial to improve the problem of pores in the molten pool of the laser weld and further improve the flow capacity.

[0027] In some embodiments, the compacted region includes a plurality of third sub-regions, and the third sub-regions are plural and spaced apart and arranged around the two first sub-regions.

[0028] In the above technical solution, multiple third sub-regions are arranged around the two first sub-regions, which helps to improve the grip during welding and provide greater friction, so that the first sub-region can be effectively compacted and the compaction rate of the first sub-region is improved. In this way, when part of the contour line of the laser weld falls on the first sub-region, the problem of thermal cracks in this part of the contour line can be further improved.

[0029] In some embodiments, the gathering portion includes a fluffy area, the fluffy area includes a second fluffy area arranged on the periphery of the two first sub-areas, and separated between the first sub-area and the third sub-area and between two adjacent third sub-areas, and the second fluffy area is in the form of a line on the outer surface of the gathering portion so that the outline of the third sub-area matches the outline of the first sub-area.

[0030] In the above technical solution, a second fluffy area in the form of a line is set to separate the first sub-area and the third sub-area, and to separate the adjacent third sub-area, so that the contour of the third sub-area matches the contour of the first sub-area, that is, the protruding position of the contour of the first sub-area corresponds to the recessed position of the contour of the third sub-area, the spacing between adjacent third sub-areas is small, and the spacing between the first sub-area and the third sub-area is small, so that the spatial structure compaction area of ​​the gathered part can be more fully utilized to improve the grip during welding, to provide greater friction, and to improve the compaction rate of the first sub-area. In this way, when part of the contour line of the laser weld falls on the first sub-area, the problem of thermal cracks in this part of the contour line can be further improved.

[0031] In some embodiments, the compaction area includes a plurality of first compaction rows spaced apart along the width direction of the gathering portion, each first compaction row includes a plurality of fourth sub-areas spaced apart along the length direction of the gathering portion, the two long sides of the surface portion are respectively arranged corresponding to two of the first compaction rows, and each long side passes through a plurality of fourth sub-areas in the corresponding first compaction row, and the size of the fourth sub-area in the length direction of the gathering portion is larger than the spacing between two adjacent fourth sub-areas in the length direction of the gathering portion.

[0032] In the above technical solution, by configuring the compacted area to include multiple fourth sub-areas arranged in the aforementioned manner, configuring the size of the fourth sub-areas in the longitudinal direction of the gathered portion to be greater than the spacing between two adjacent fourth sub-areas in the longitudinal direction of the gathered portion, and arranging the two long sides of the surface portion of the connecting portion to correspond to the two first compacted rows, with each long side passing through multiple fourth sub-areas in the corresponding first compacted row, the majority of the surface portion's contour line can fully utilize the compacted area, increasing the portion of the surface portion's contour line that falls within the compacted area, thereby alleviating the risk of thermal cracking within the surface portion's contour, improving the conductivity yield and connection strength between the gathered portion and the conductive portion, and thereby enhancing the reliability of the battery cell. Furthermore, as the internal portion extends from the surface portion toward the conductive portion, the majority of the internal portion can also fall within the fourth sub-area, thereby increasing the volume of the internal portion that falls within the compacted area, further alleviating the risk of air holes within the internal portion, and thereby further improving the current carrying capacity.

[0033] In some embodiments, there are two first compaction rows, the fourth sub-region is long and narrow, and the length direction of the fourth sub-region matches the width direction of the gathered portion, the width direction of the fourth sub-region matches the length direction of the gathered portion, and the length of the fourth sub-region exceeds one-quarter of the width of the gathered portion.

[0034] In the above technical solution, the fourth sub-region can make full use of the space of the gathered part, and the area of ​​the fourth sub-region is relatively large. When the contour line of the laser weld passes through multiple fourth sub-regions, it is beneficial to improve the problem of thermal cracks in the contour line of the laser weld and improve the problem of pores in the molten pool of the laser weld, thereby improving the conductive yield and connection strength between the gathered part and the conductive part.

[0035] In some embodiments, the gathering portion includes a fluffy area, the fluffy area includes a third fluffy area separated between two adjacent fourth sub-areas in the same first compaction row, and a fourth fluffy area separated between two adjacent first compaction rows, the third fluffy area is in the form of a line extending along the width direction of the gathering portion on the outer surface of the gathering portion, the fourth fluffy area is in the form of a line extending along the length direction of the gathering portion on the outer surface of the gathering portion, and the width of the third fluffy area is smaller than the width of the fourth fluffy area.

[0036] This technical solution helps reduce the length of the surface portion's long side falling within the third puffy zone, further improving the problem of thermal cracking along the surface portion's contour. Furthermore, because both the third and fourth puffy zones appear as lines on the outer surface of the gathered portion, this helps increase the proportion of the fourth sub-region relative to the gathered portion, and thus, the proportion of the compacted area relative to the gathered portion. This reduces the risk of thermal cracking along the laser weld contour when it passes through multiple fourth sub-regions, further improving the problem of porosity within the weld pool and thereby enhancing flow capacity.

[0037] In some embodiments, the surface portion is entirely located in the compacted region.

[0038] In the above technical solution, the entire contour of the surface portion is less susceptible to thermal cracking, effectively improving the conductivity yield and connection strength between the gathered portion and the conductive portion, and enhancing the reliability of the battery cell. Furthermore, because the connection portion extends from the outer surface of the gathered portion toward the conductive portion, when the entire surface portion is located in the compacted area, if the internal portion gradually tapers from the surface portion toward the conductive portion, the entire internal portion can also fall within the compacted area. This makes the contour of the internal portion less susceptible to thermal cracking, further improving the conductivity yield and connection strength between the gathered portion and the conductive portion, and enhancing the reliability of the battery cell. Furthermore, the internal portion is less susceptible to air holes, further improving the current carrying capacity.

[0039] In some embodiments, the compacted region includes a plurality of fifth sub-regions disposed at intervals, and the surface portion is a plurality of fifth sub-regions disposed at intervals and arranged in a one-to-one correspondence with the plurality of fifth sub-regions.

[0040] In the above technical solution, by setting the compaction area to include multiple fifth sub-areas arranged at intervals, and setting multiple surface parts in one-to-one correspondence with multiple fifth sub-areas, it can be simply and effectively achieved that the entire surface part is located in the compaction area, and the total area of ​​the surface parts added together is relatively large, meeting the flow capacity requirements, and if the internal part presents a shape that gradually shrinks as a whole from the surface part to the conductive part, the internal parts extending from each surface part can also fall in the fifth sub-area respectively, so that the contour of the internal part is not prone to thermal cracks, and the internal part is not prone to pores, which is beneficial to improve the conductivity yield and connection strength between the gathered part and the conductive part, improve the flow capacity, and enhance the reliability of the battery cell.

[0041] In some embodiments, the compacted area includes a plurality of second compacted rows spaced apart along a width direction of the gathered portion, and each second compacted row includes a plurality of fifth sub-areas spaced apart along a length direction of the gathered portion.

[0042] In the above technical solution, by setting the compaction area to include multiple fifth sub-areas in the above arrangement form, the arrangement of the fifth sub-areas can be simplified, making it easier to find each fifth sub-area for separate laser welding. Moreover, it is beneficial to simplify the design of the compaction area, making the gathered part easy to process, and reducing the design and processing difficulty of the welding head used to process the gathered part.

[0043] In some embodiments, there are two second compacted rows, and the dimensions of the fifth sub-region in the width direction and in the length direction of the gathered portion are both greater than a quarter of the width of the gathered portion.

[0044] In the above technical solution, by setting the second compaction row to two and setting the fifth sub-area so that the dimensions in the width direction and the length direction of the gathering portion are both greater than one-quarter of the width of the gathering portion, the area of ​​each fifth sub-area is relatively large, which is beneficial to reducing the number of fifth sub-areas, reducing the number of welding times, and making the area of ​​each surface portion relatively large, which is convenient for processing and improves the flow capacity.

[0045] In some embodiments, the connecting portion includes a first connecting portion and a second connecting portion, the second connecting portion extends into the conductive portion, the extension depth of the first connecting portion is less than the extension depth of the second connecting portion, the surface portion includes a first surface portion of the first connecting portion formed on the outer surface of the converged portion, and a second surface portion of the second connecting portion formed on the outer surface of the converged portion, and at least most of the contour line of the second surface portion is located within the first surface portion.

[0046] In the above technical solution, because the extension depth of the second connecting portion is greater than that of the first connecting portion, the second connecting portion can extend into the conductive portion, thereby forming a portion of the second connecting portion within the gathered portion and the remaining portion within the conductive portion. The second connecting portion can thus serve to connect the gathered portion and the conductive portion. Furthermore, because the extension depth of the first connecting portion is less than that of the second connecting portion, the energy required for laser welding the first connecting portion is less, and the contour of the first connecting portion is less susceptible to thermal cracking. Furthermore, because at least a majority of the contour of the second surface portion lies within the first surface portion, at least a majority of the contour of the second surface portion on the outer surface of the gathered portion can fall within the first surface portion, thereby alleviating the risk of thermal cracking within the contour of the second surface portion. Furthermore, at least a portion of the contour of the molten pool formed by the second connecting portion can also lie within the first connecting portion, thereby facilitating the reduction of thermal cracking within the contour of the molten pool of the second connecting portion and improving the electrical conductivity yield and connection strength between the conductive portion and the gathered portion.

[0047] In some embodiments, the shape of the first face matches the shape of the contour of the second face, and at least a majority of the contour of the second face falls in the center of the first face.

[0048] In the above technical solution, by setting the shape of the first face portion to match the shape of the contour line of the second face portion, it is beneficial to make the contour line of the second face portion fall more within the first face portion, thereby helping to further improve the problem of thermal cracks in the contour line of the second face portion. Furthermore, when laser welding is performed, the first connection portion and the second connection portion can respectively present a shape that extends and gradually shrinks along the thickness direction of the converged portion as a whole. By setting at least most of the contour line of the second face portion in the central position of the first face portion, it is beneficial for the molten pool contour extending from the second connection portion to the converged portion to fall more within the first connection portion, thereby helping to further improve the problem of thermal cracks in the contour of the second connection portion.

[0049] In some embodiments, the surface of the gathering portion is long and strip-shaped, the surface portion is long and strip-shaped and matches the length direction of the gathering portion, the first face portion is long and strip-shaped extending along the length direction of the gathering portion and two are spaced apart along the width direction of the gathering portion, and the second face portion is long and strip-shaped extending along the length direction of the gathering portion, and the two long sides of the second face portion fall within the two first faces respectively.

[0050] In the above technical solution, one long side of the second face can fall within one of the first face parts, and the other long side of the second face can fall within the other first face part, so that the two long sides of the second face can be respectively located within the first connecting part, and most of the contour of the second face is not prone to thermal cracks. Moreover, the contour of the molten pool extending from the two long sides of the second face to the convergent part can also be mostly located within the first connecting part, thereby improving the problem of thermal cracks in the contour of the second connecting part and improving the conductivity yield and connection strength between the convergent part and the conductive part.

[0051] In some embodiments, the surface portions are multiple and spaced apart, each surface portion includes a first face portion and a second face portion, the first face portion is annular and surrounds the corresponding second face portion, and the contour line of the second face portion is located within the corresponding first face portion.

[0052] In the above technical solution, the contour of the second face part all falls within the corresponding first face part, so that the contour line of the second face part is located within the first connecting part all around. The contour of the second face part is not prone to thermal cracks. Moreover, the contour of the molten pool extending from the contour of the second face part to the convergent part can also be mostly located within the first connecting part, thereby improving the problem of thermal cracks in the contour of the second connecting part and improving the conductivity yield and connection strength between the convergent part and the conductive part.

[0053] In some embodiments, the first connecting portion extends to a depth of 60% to 100% of the thickness of the compacted region.

[0054] In the above technical solution, the first connecting portion extends from the surface of the converged portion only into the converged portion, and the extension depth exceeds half the thickness of the compacted region. In this case, the molten pool depth of the first connecting portion is relatively small, requiring less energy during welding, making the profile less susceptible to thermal cracking, which helps improve the conductivity yield and connection strength between the converged portion and the conductive portion. Furthermore, the molten pool depth of the first connecting portion is not too small, allowing the profile of the second connecting portion to fit more deeply into the first connecting portion, thereby reducing the risk of thermal cracking in the second connecting portion.

[0055] In some embodiments, the connecting portion also includes a third connecting portion, the extension depth of the third connecting portion is less than the extension depth of the first connecting portion, the third connecting portion is arranged on the side of the first connecting portion away from the second connecting portion, and the surface portion also includes a third surface portion formed by the third connecting portion on the outer surface of the converged portion, and at least part of the contour line of the first surface portion is located within the third surface portion.

[0056] In the above technical solution, because the extension depth of the third connecting portion is less than that of the first connecting portion, the energy required for laser welding is less, making the third connecting portion's profile less susceptible to thermal cracking. Furthermore, because the third connecting portion is located on the side of the first connecting portion away from the second connecting portion, at least a portion of the first surface's contour lies within the third surface, thereby alleviating the risk of thermal cracking within the first surface's contour. Furthermore, at least a portion of the contour of the molten pool formed by the first connecting portion also lies within the third connecting portion, thereby alleviating the risk of thermal cracking within the first connecting portion's molten pool contour and improving the electrical conductivity yield and connection strength between the conductive portion and the convergent portion.

[0057] In some embodiments, at least a majority of the contour of the first face portion is located within the third face portion.

[0058] In the above technical solution, most of the contour of the first face portion can be repaired by the third connecting portion, thereby more effectively improving the problem of thermal cracks in the contour of the first face portion.

[0059] In some embodiments, the shape of the third face portion matches the shape of the outline of the first face portion, and at least a majority of the outline of the first face portion falls within a central position of the third face portion.

[0060] In the above technical solution, by setting the shape of the third face portion to match the contour line shape of the first face portion, it is beneficial to make the contour line of the first face portion fall more within the third face portion, thereby helping to further improve the problem of thermal cracks in the contour line of the first face portion. Furthermore, when laser welding is performed, the first connection portion and the third connection portion can respectively present a shape that extends and gradually shrinks along the thickness direction of the convergence portion as a whole. By setting at least most of the contour line of the first face portion in the central position of the third face portion, it is beneficial for the molten pool contour extending from the first connection portion to the convergence portion to fall more within the third connection portion, thereby helping to further improve the problem of thermal cracks in the contour of the first connection portion.

[0061] In some embodiments, the third connecting portion extends to a depth of 20% to 60% of the thickness of the compacted region.

[0062] In the above technical solution, the third connecting portion extends only from the surface of the converged portion into the interior of the converged portion. The molten pool depth of the third connecting portion is relatively small, requiring less energy during welding. This reduces the risk of thermal cracking in the contour, thus improving the electrical conductivity yield and connection strength between the converged portion and the conductive portion. Furthermore, the molten pool depth of the third connecting portion is not too small, allowing the contour of the first connecting portion to fit more deeply into the third connecting portion, thereby alleviating the risk of thermal cracking in the contour of the first connecting portion.

[0063] In some embodiments, the first portion includes an inner portion formed within the gather, and at least a majority of a contour of the inner portion falls within the compacted region.

[0064] In the above technical solution, since at least most of the contour line of the portion where the connection portion is formed within the gathered portion is arranged within the compacted area, the multiple layers of the pole tabs in the compacted area are very tightly combined together with no or almost no interlayer gaps, thereby improving the problem of thermal cracks in the weld contour caused by the interlayer gaps, thereby improving the conductivity yield and connection strength between the pole tab portion and the conductive portion, and improving the reliability of the battery cell.

[0065] In some embodiments, more than 60% of the contour of the interior portion falls within the compacted region.

[0066] In the above technical solution, by setting the contour of the inner portion to fall within the compacted area, more than 60% of the contour of the inner portion can be further improved, thereby further alleviating the problem of thermal cracking of the molten pool contour where the connection portion is located within the gathered portion. Furthermore, when the connection portion extends from the outer surface of the gathered portion toward the conductive portion, the majority of the contour of the first portion is the contour of the inner portion. When more than 60% of the contour of the inner portion falls within the compacted area, this helps increase the proportion of the contour of the first portion that falls within the compacted area relative to the contour of the fluffy area. This can overall improve the problem of thermal cracking of the contour of the first portion of the connection portion formed within the gathered portion, further enhance the conductivity yield and connection strength between the tab portion and the conductive portion, and improve the reliability of the battery cell.

[0067] In some embodiments, at least a majority of the volume of the interior portion falls within the compacted region.

[0068] In the above technical solution, since there is no or almost no interlayer gap between the multilayer tab sheets in the compacted area, pores caused by interlayer gaps are not likely to appear in the molten pool in the compacted area. This embodiment helps to reduce the pores formed in the internal part by setting at least most of the volume of the internal part in the compacted area, thereby improving the flow energy of the connection part.

[0069] In some embodiments, the area of ​​the compacted region relative to the area of ​​the converged portion accounts for greater than or equal to 40%.

[0070] In the above technical solution, by setting the area ratio of the compacted area to be greater than or equal to 40%, it is beneficial to increase the coverage of the compacted area on the gathered part, which is beneficial to the design of the connection part, so that the connection part can be distributed more in the compacted area, improving the problem of thermal cracks in the contour of the connection part, improving the conductivity yield and connection strength of the pole ear and the conductive part, improving the problem of air holes in the connection part, and improving the current flow capacity of the connection part, thereby improving the reliability of the battery cell.

[0071] In some embodiments, the area ratio of the compacted region to the converged portion is greater than or equal to 60%.

[0072] In the above technical solution, by setting the area ratio of the compacted area to be greater than or equal to 60%, most of the gathered part can be the compacted area, which is beneficial to the design of the connection part, so that the connection part can be distributed more in the compacted area, improving the problem of thermal cracks in the contour of the connection part, improving the conductivity yield and connection strength between the pole ear and the conductive part, improving the problem of air holes in the connection part, and improving the current flow capacity of the connection part, thereby improving the reliability of the battery cell.

[0073] In some embodiments, the compaction rate of the compacted region is greater than or equal to 6%.

[0074] In the above technical solution, by setting the compaction rate of the compaction area to be greater than or equal to 6%, the interlayer gap in the compaction area can be reduced, and the part of the connection part that enters the compaction area is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connection part, as well as the reliability and conductivity yield of the connection part connecting the conductive part and the gathered part.

[0075] In some embodiments, the compaction rate of the compacted region is greater than or equal to 12%.

[0076] In the above technical solution, by setting the compaction rate of the compaction area to be greater than or equal to 12%, the gap in the compaction area can be further reduced, so that there is almost no gap in the compaction area, and the part where the connecting part enters the compaction area is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connection part, as well as the reliability and conductivity yield of the connection part connecting the conductive part and the gathered part.

[0077] In a second aspect, an embodiment of the present application further provides a battery comprising a battery cell according to any of the above solutions.

[0078] In the above technical solution, since the reliability of the battery cells is improved, it is beneficial to improve the reliability of the battery.

[0079] In a third aspect, an embodiment of the present application further provides an electrical device comprising a battery cell according to any of the above solutions.

[0080] In the above technical solution, since the reliability of the battery is improved, it is beneficial to improve the working power performance of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0082] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0083] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0084] FIG3 is a perspective view of a battery cell provided in some embodiments of the present application;

[0085] FIG4 is a top view of a battery cell provided in some embodiments of the present application;

[0086] FIG5 is a cross-sectional view along line DD in FIG4 ;

[0087] FIG6 is a partial enlarged view of portion B in FIG5 ;

[0088] FIG7 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0089] FIG8 is a schematic diagram of ultrasonic pre-welding of a tab portion by an ultrasonic welding device provided in some embodiments of the present application;

[0090] FIG9 is a partial enlarged view of portion C in FIG8 ;

[0091] FIG10 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0092] FIG11 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0093] FIG12 is a partial cross-sectional view of welding of a tab portion and a conductive portion according to some embodiments of the present application;

[0094] FIG13 is a schematic diagram of a gathering portion provided in some embodiments of the present application;

[0095] FIG14 is a schematic diagram of welding a gathered portion and a conductive portion according to some embodiments of the present application;

[0096] FIG15 is a schematic diagram of welding a gathered portion and a conductive portion according to some embodiments of the present application;

[0097] FIG16 is a schematic diagram of a first face and a second face provided by some embodiments of the present application;

[0098] FIG17 is a schematic diagram of the first face portion shown in FIG16 ;

[0099] FIG18 is a schematic diagram of the second face portion shown in FIG16 ;

[0100] FIG19 is a schematic diagram of a first face and a second face provided by some embodiments of the present application;

[0101] FIG20 is a schematic diagram of the first face portion shown in FIG19 ;

[0102] FIG21 is a schematic diagram of the second face portion shown in FIG19 ;

[0103] FIG22 is a partial cross-sectional morphology diagram of the gathered portion of Comparative Example 1;

[0104] FIG23 is a partial cross-sectional morphology of the gathered portion and the conductive portion of Comparative Example 1 after laser welding;

[0105] FIG24 is a partial cross-sectional morphology diagram of the gathered portion of Comparative Example 2;

[0106] FIG25 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion of Comparative Example 2 after laser welding;

[0107] FIG26 is a partial cross-sectional morphology diagram of the convergent portion of Comparative Example 3;

[0108] FIG27 is a partial cross-sectional morphology of the gathered portion and the conductive portion of Comparative Example 3 after laser welding;

[0109] FIG28 is a partial cross-sectional topographic view of the gathered portion of Example 1;

[0110] FIG29 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 1;

[0111] FIG30 is a partial cross-sectional topographic view of the gathered portion of Example 2;

[0112] FIG31 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 2;

[0113] FIG32 is a partial cross-sectional topography of the gathered portion of Example 3;

[0114] FIG33 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding in Example 3;

[0115] FIG34 is a partial cross-sectional topographic view of the gathered portion of Example 4;

[0116] FIG35 is a partial cross-sectional morphology diagram of the gathered portion and the conductive portion after laser welding of the fourth embodiment;

[0117] FIG36 is a front view of an ultrasonic welding device provided in some embodiments of the present application;

[0118] FIG37 is a left side view of the ultrasonic welding device shown in FIG36;

[0119] FIG38 is a front view of a welding head provided in some embodiments of the present application;

[0120] FIG39 is a side view of a welding head provided in some embodiments of the present application;

[0121] FIG40 is a topographical diagram of an ultrasonic weld mark produced by the ultrasonic welding apparatus shown in FIG38 ;

[0122] FIG41 is a topographical diagram of the ultrasonic weld mark and the conductive portion shown in FIG40 after laser welding;

[0123] FIG42 is a cross-sectional view along line AA in FIG41;

[0124] FIG43 is a partial enlarged view of portion L in FIG42;

[0125] FIG44 is a partial enlarged view of the R portion in FIG42;

[0126] FIG45 is a side view of a welding head provided in some embodiments of the present application;

[0127] FIG46 is a topographical diagram of an ultrasonic weld mark produced by the ultrasonic welding apparatus shown in FIG45 ;

[0128] FIG47 is a topographical image of the ultrasonic weld mark and the conductive portion shown in FIG46 after laser welding;

[0129] FIG48 is a partial cross-sectional morphology diagram of the laser weld shown in FIG47 ;

[0130] FIG49 is a side view of a welding head provided in some embodiments of the present application;

[0131] FIG50 is a topographical diagram of an ultrasonic weld mark produced by the ultrasonic welding apparatus shown in FIG49;

[0132] FIG51 is a cross-sectional topography of the ultrasonic weld mark shown in FIG50;

[0133] FIG52 is a schematic diagram of the ultrasonic welding local welding bottom weld shown in FIG51;

[0134] FIG53 is a cross-sectional topography of the bottom weld shown in FIG52;

[0135] FIG54 is a schematic diagram of welding a main weld on the base weld shown in FIG52;

[0136] Figure 55 is a cross-sectional morphology diagram of the base weld and the main weld shown in Figure 54.

[0137] 1000 ; battery 100 ; controller 200 ; motor 300 ; housing 101 ; first housing body 1011 ; second housing body 1012 ; battery cell 102 ; first direction X ; second direction Y ; third direction Z ; fourth direction E ; fifth direction F ; housing component 1 ; first housing wall 11 ; accommodating cavity 12 ; pole component 2 ; conductive portion 20 ; pole body 21 ; electrode assembly 3 ; active material coating portion 31 ; pole lug portion 32 ; pole lug sheet 320 ; gathered portion 321 ; compacted region 3211 ; first sub-region Z1 ; protruding section Z11 ; second sub-region Z2 ; third sub-region Z3 ; region 1 Z31 ; region 2 Z32 ; first compacted row Z4 ; fourth sub-region Z5 ; fifth sub-region Z6 ; second compacted row Z7 ; fluffy region 3212 ; first fluffy zone L1 ; second fluffy zone L2 ; Third bulky region L3; fourth bulky region L4; fifth bulky region L5; sixth bulky region L6; connecting portion 4; first portion 41; surface portion 411; outline 4x of surface portion; long side 4x1 of surface portion; short side 4x2 of surface portion; inner portion 412; outline 4y of inner portion; second portion 42; first connecting portion 4a; first face portion 4a1; second connecting portion 4b; second face portion 4b1; third connecting portion 4c; third face portion 4c1; ultrasonic welding device 2000; welding head 400; welding end 401; welding tooth 5; tooth portion 51; first tooth portion 514; protrusion 5141; second tooth portion 515; third tooth portion 516; first sub-tooth 5161; second sub-tooth 5162; fourth tooth portion 513; fifth tooth portion 517; tooth groove 6; first linear groove 61; second linear groove 62; Welding seat 500; driving cylinder 600. DETAILED DESCRIPTION

[0138] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0139] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0140] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0141] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0142] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0143] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0144] The term "plurality" used in this application refers to two or more (including two).

[0145] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0146] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery module generally includes multiple battery cells. A battery pack generally includes a casing for enclosing one or more battery cells or one or more battery modules. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0147] A battery cell consists of a housing, an electrode assembly, and an electrolyte. The housing houses the electrode assembly and electrolyte. The housing contains at least one electrode assembly, which consists of a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly can be a wound or stacked structure. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets.

[0148] A positive electrode sheet generally includes a positive current collector and a positive active material layer. The positive active material layer is directly or indirectly coated on the positive current collector. The uncoated positive current collector protrudes from the coated positive current collector, serving as the positive tab. For lithium-ion batteries, for example, the positive current collector can be made of aluminum, and the positive active material layer can be made of lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide.

[0149] A negative electrode sheet generally includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is directly or indirectly coated on the negative electrode current collector. The negative electrode current collector not coated with the negative electrode active material layer protrudes from the negative electrode current collector coated with the negative electrode active material layer, and the negative electrode current collector not coated with the negative electrode active material layer serves as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material layer can be made of carbon, silicon, or other materials.

[0150] To ensure high current flow without melting, multiple positive electrode tabs are stacked together to form the positive electrode tab, while multiple negative electrode tabs are stacked together to form the negative electrode tab. The housing is provided with a post component, with the positive electrode tab electrically connected to the positive electrode post component and the negative electrode tab electrically connected to the negative electrode post component.

[0151] During the battery cell production process, ultrasonic welding can be used to pre-weld multiple tabs in the tab section to form an ultrasonic weld mark. This weld mark is then laser welded to the conductive portion of the pole post, achieving a connection and electrical continuity between the electrode assembly and the pole post. However, the laser weld seam profile is susceptible to thermal cracking, which affects the conductivity yield and connection strength between the tab and the conductive portion, and thus the reliability of the battery cell.

[0152] To this end, embodiments of the present application propose a battery cell in which multiple tabs are connected to form a gathered portion. The gathered portion overlaps and connects with the conductive portion to form a connecting portion. The gathered portion includes a compacted region whose thickness is less than the stacked thickness of the multiple tabs in the tab portion. The connecting portion includes a first portion formed in the gathered portion and a second portion formed in the conductive portion. At least a majority of the contour of the first portion lies within the compacted region. Thus, because at least a majority of the contour of the portion of the connecting portion formed on the gathered portion lies within the compacted region, the multiple tabs in the compacted region are very tightly bonded together, thereby improving the problem of thermal cracking in the contour of the connecting portion, enhancing the conductivity yield and connection strength between the tab portion and the conductive portion, and improving the current carrying capacity and reliability of the battery cell.

[0153] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0154] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device according to an embodiment of the present application.

[0155] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0156] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000 , but also as a driving power source for the vehicle 1000 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000 .

[0157] Please refer to Figure 2, which is an exploded view of the structure of the battery 100 provided in some embodiments of the present application. The battery 100 includes a box body 101 and a plurality of battery cells 102, and the battery cells 102 are accommodated in the box body 101. The box body 101 is used to provide an assembly space for the battery cells 102, and the box body 101 can adopt a variety of structures. In some embodiments, the box body 101 may include a first box body 1011 and a second box body 1012, and the first box body 1011 and the second box body 1012 cover each other, and the first box body 1011 and the second box body 1012 jointly define an assembly space for accommodating the battery cells 102. The second box body 1012 can be a hollow structure with one end open, and the first box body 1011 can be a plate-shaped cover structure, with the first box body 1011 covering the open side of the second box body 1012, so that the first box body 1011 and the second box body 1012 jointly define an assembly space; the first box body 1011 and the second box body 1012 can also be hollow structures with one side open, with the open side of the first box body 1011 covering the open side of the second box body 1012. Of course, the box body 101 formed by the first box body 1011 and the second box body 1012 can be of various shapes, such as a cylinder, a cuboid, etc.

[0158] In the battery 100, multiple battery cells 102 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections within the multiple battery cells 102. Multiple battery cells 102 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure formed by the multiple battery cells 102 is housed within the housing 101. Alternatively, the battery 100 can be constructed by first connecting multiple battery cells 102 in series, in parallel, or in a hybrid configuration to form a battery module. The multiple battery modules are then connected in series, in parallel, or in a hybrid configuration to form a single structure, which is then housed within the housing 101. The battery 100 may also include other structures, such as a busbar assembly for electrically welding the multiple battery cells 102 together.

[0159] Each battery cell 102 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 102 can be cylindrical, flat, or rectangular. For example, referring to the embodiment shown in FIG3 , the length of the battery cell 102 is a first direction X, the width of the battery cell 102 is a second direction Y, and the height of the battery cell 102 is a third direction Z. The first direction X, the second direction Y, and the third direction Z are mutually perpendicular.

[0160] Please refer to Figures 3-7. Figure 3 is a perspective view of a battery cell 102 according to some embodiments of the present application. Figure 4 is a top view of the battery cell 102 shown in Figure 3. Figure 5 is a cross-sectional view taken along line DD in Figure 4. Figure 6 is a partial enlarged view of section B in Figure 5. Figure 7 is a partial cross-sectional view of the connection between the conductive portion 20 and the retracted portion 321 according to some embodiments of the present application. In some embodiments of the present application, the battery cell 102 includes: a housing component 1, a post component 2, and an electrode assembly 3. The post component 2 is disposed in the housing component 1 and includes a conductive portion 20. The electrode assembly 3 is housed in the housing component 1 and includes a tab portion 32. The tab portion 32 includes a plurality of tab sheets 320 stacked in a stack. The plurality of tab sheets 320 are connected to form a retracted portion 321. The retracted portion 321 overlaps and connects with the conductive portion 20 to form a connecting portion 4.

[0161] For example, in conjunction with Figures 3 to 6, the shell component 1 may include a first shell wall 11, and the pole component 2 is arranged on the first shell wall 11. The structure of the shell component 1 is not limited. For example, the shell component 1 may include a shell body and a shell cover, the shell body defines a cavity with one end closed and the other end open, and the shell cover is provided on the open end of the shell body, wherein the shell cover can serve as the first shell wall 11, or the end wall surface of the shell body opposite to the shell cover can also serve as the first shell wall 11. For another example, the shell component 1 may include two half shells arranged in opposition, each half shell defining a cavity open toward the other half shell, and the end wall surface of one half shell away from the other half shell serves as the first shell wall 11.

[0162] 5 and 6 , the pole component 2 includes a conductive portion 20, which is the portion of the pole component 2 used to connect to the electrode assembly 3. For example, the conductive portion 20 may be the pole body 21. In this case, the gathered portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the pole body 21. For another example, the conductive portion 20 may also be an adapter plate connected to the pole body 21. In this case, the gathered portion 321 formed by connecting the tabs 320 in the electrode assembly 3 is directly electrically connected to the adapter plate, which is electrically connected to the pole body 21, thereby indirectly electrically connecting the gathered portion 321 to the pole body 21 via the adapter plate. To simplify the description, the following description mainly uses the pole body 21 as an example for the conductive portion 20.

[0163] 5 and 6 , the electrode assembly 3 includes an active material coating portion 31 housed within the housing component 1, and a pole ear portion 32 connected to the active material coating portion 31. Exemplarily, a housing cavity 12 is formed within the housing component 1, the active material coating portion 31 is housed within the housing cavity 12, the pole body 21 is passed through the first shell wall 11, and the pole ear portion 32 is welded to the pole body 21. The pole ear portion 32 is directly electrically connected to the pole body 21, so that the pole ear portion 32 is electrically connected between the active material coating portion 31 and the pole body 21.

[0164] 6 and 7 , the multiple tabs 320 in the tab portion 32 are stacked and connected to form a gathered portion 321. Specifically, the portion where the multiple tabs 320 are connected together by the connection process constitutes the gathered portion 321. Therefore, the multiple tabs 320 in the gathered portion 321 are not only stacked but also connected. The thickness side of the gathered portion 321 faces the conductive portion 20 and is disposed on the conductive portion 20, thereby achieving overlap between the gathered portion 321 and the conductive portion 20. The gathered portion 321 and the conductive portion 20 are connected together by the connection process, and the connected portion forms the connecting portion 4.

[0165] The connection method of the multiple tabs 320 in the gathered portion 321 is not limited, and may be, for example, welding, punching, or adhesive connection. The connection method of the gathered portion 321 and the conductive portion 20 is not limited, and may be, for example, welding, punching, or adhesive connection. For simplicity of description, the following mainly uses ultrasonic welding of the multiple tabs 320 in the gathered portion 321 and laser welding of the gathered portion 321 and the conductive portion 20 as examples for description. The gathered portion 321 is ultrasonically welded, and the connecting portion 4 is a laser weld.

[0166] In the embodiment of the present application, with reference to Figures 7 to 9 , the gathered portion 321 includes a compacted region 3211, and the thickness T1 of the compacted region 3211 is less than the theoretical thickness T2 of the pole lug portion 32. Therefore, since the thickness T1 of the compacted region 3211 of the gathered portion 321 is less than the theoretical thickness T2 of the pole lug portion 32, it indicates that the pole lug 320 in the compacted region 3211 is compressed and yielded and undergoes plastic deformation, resulting in a reduction in the thickness of the pole lug 320. Furthermore, the multiple layers of pole lug 320 in the compacted region 3211 are tightly bonded together, with little or no interlayer gaps, and the compaction rate of the compacted region 3211 is greater than 0%.

[0167] The "compaction rate" of the gathered portion 321 refers to the ratio of the difference between the theoretical thickness T2 of the tab portion 32 and the thickness T1 of the compacted region 3211 to the theoretical thickness T2 of the tab portion 32, i.e., (T2-T1) / T2. The theoretical thickness T2 refers to the stacked thickness of the multiple tab sheets 320 in the tab portion 32, i.e., the thickness of the tab sheets 320 when they are uncompressed and stacked together without gaps. For example, if the thickness of a single tab sheet 320 is a (i.e., a is the thickness of a single layer of foil), and there are b layers of tab sheets 320 stacked in the tab portion 32 (i.e., b is the number of foil layers), then the stacked thickness of the multiple tab sheets 320 in the tab portion 32 is a×b, and therefore the theoretical thickness T2 of the tab portion 32 is a×b.

[0168] For example, in combination with Figures 8 and 9, ultrasonic welding is used to process the gathered portion 321. The welding head 400 used in the ultrasonic welding process has welding teeth 5 and tooth grooves 6. The welding teeth 5 are separated by the tooth grooves 6 into a plurality of tooth portions 51 arranged at intervals, that is, the tooth grooves 6 are the inter-tooth gaps between the multiple tooth portions 51 of the welding teeth 5. After welding, the area on the gathered portion 321 corresponding to the tooth portion 51 is the compacted area 3211, and the area on the gathered portion 321 corresponding to the tooth grooves 6 is the fluffy area 3212. The multi-layer pole tabs 320 in the compacted area 3211 are effectively welded and fused together, and there is no or almost no interlayer gap between the foils. The multi-layer pole tabs 320 in the fluffy area 3212 are not effectively fused together, and there are interlayer gaps between the multi-layer pole tabs 320.

[0169] In the embodiment of the present application, please refer to Figures 6 and 7 again. The connecting part 4 includes a first part 41 formed on the gathering part 321, and a second part 42 formed on the conductive part 20. It can be understood that the connecting part 4 needs to connect the conductive part 20 and the gathering part 321, so a part of the connecting part 4 will be formed on the gathering part 321, which is the first part 41, and the remaining part will be formed on the conductive part 20, which is the second part 42.

[0170] For example, with reference to FIG7 , when laser welding is performed from the side of the gathered portion 321 facing away from the conductive portion 20, the first portion 41 of the connecting portion 4 formed on the gathered portion 321 may include: a surface portion 411 formed on the outer surface of the gathered portion 321, and an inner portion 412 formed within the gathered portion 321. In this case, the outline 4x of the surface portion 411 and the outline 4y of the inner portion 412 constitute the outline of the first portion 41. Alternatively, if laser welding is performed from the side of the conductive portion 20 facing away from the gathered portion 321, the first portion 41 of the connecting portion 4 formed on the gathered portion 321 may include only: the inner portion 412 formed within the gathered portion 321. In this case, the outline 4y of the inner portion 412 constitutes the outline of the first portion 41.

[0171] At least a majority of the contour of the first portion 41 lies within the compacted region 3211. That is, at least a majority of the contour of the portion of the connecting portion 4 formed on the gathered portion 321 lies within the compacted region 3211. Since at least a majority of the contour of the portion of the connecting portion 4 formed on the gathered portion 321 lies within the compacted region 3211, this indicates that at least 50% (including 50%) of the contour of the portion of the connecting portion 4 formed on the gathered portion 321 lies within the compacted region 3211. For example, the contour of the portion of the connecting portion 4 formed on the gathered portion 321 may lie entirely within the compacted region 3211. For another example, a portion of the contour of the portion of the connecting portion 4 formed on the gathered portion 321 may lie within the compacted region 3211, while the remainder of the contour may lie within the puffy region 3212. In this case, the proportion of the contour that lies within the compacted region 3211 is greater than the proportion that lies within the puffy region 3212.

[0172] In this way, in the above technical solution, since at least most of the contour line of the portion of the connecting portion 4 formed on the gathered portion 321 is set in the compacted area 3211, the multi-layer pole tab sheets 320 in the compacted area 3211 are very tightly combined together with no or almost no interlayer gaps, thereby improving the problem of thermal cracks in the contour of the weld caused by the interlayer gaps, thereby improving the conductive yield and connection strength between the pole tab portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0173] In some embodiments of the present application, referring to FIG7 , the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20 , and the first portion 41 includes a surface portion 411 formed on the outer surface of the gathered portion 321 and an inner portion 412 formed within the gathered portion 321 . The “outer surface of the gathered portion 321 ” refers to the surface of the gathered portion 321 that is away from the conductive portion 20 .

[0174] Exemplarily, when laser welding is used to obtain the connecting portion 4, laser welding can be performed from the side of the gathered portion 321 facing away from the conductive portion 20. The connecting portion 4 is a laser weld, and the molten pool of the laser weld extends from the gathered portion 321 to the conductive portion 20. The molten pool can generally present a shape that extends as a whole along the thickness direction of the gathered portion 321 and gradually shrinks. The portion of the laser weld located on the surface of the gathered portion 321 is the surface portion 411 of the first portion 41, the portion of the molten pool located inside the gathered portion 321 is the internal portion 412 of the first portion 41, and the portion of the molten pool located inside the conductive portion 20 is the second portion 42.

[0175] Therefore, by setting the extension direction of the connecting portion 4 to be from the gathering portion 321 to the conductive portion 20, it is convenient for the welding head 400 to align with the gathering portion 321, so that the welding head 400 can reasonably design the welding trajectory according to the distribution of the compacted area 3211 and the fluffy area 3212 on the gathering portion 321, and accurately weld along the welding trajectory, so that at least most of the contour line of the part of the connecting portion 4 formed on the gathering portion 321 can be reliably located in the compacted area 3211, thereby effectively improving the conductive yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the current flow capacity and reliability of the battery cell 102.

[0176] In an embodiment of the present application, when the connection portion 4 is a laser weld, it may include only one weld, which is completed in one welding, or it may include multiple welds superimposed on each other, which are completed in multiple weldings. In this case, the total weld formed by the fusion of the multiple welds constitutes the connection portion 4. For example, in conjunction with Figure 10, the laser weld may include a base weld (such as the first connection portion 4a marked in Figure 10), a main weld (such as the second connection portion 4b marked in Figure 10) and a repair weld (such as the third connection portion 4c marked in the figure) welded in sequence. In this case, the total weld formed by the fusion of the three welds constitutes the connection portion 4. For another example, in conjunction with Figure 11, the repair weld may be omitted, and the base weld (such as the first connection portion 4a marked in Figure 11) and the main weld (such as the second connection portion 4b marked in Figure 11) may be welded in sequence. In this case, the total weld formed by the fusion of the two welds constitutes the connection portion 4. For another example, in conjunction with FIG7 , the repair weld and the base weld may be omitted, and only one main weld (eg, the second connection portion 4 b marked in FIG7 ) may be welded, and the connection portion 4 may be formed by the main weld.

[0177] In some embodiments, referring to Figures 10 and 12 , when the connection portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, at least a majority of the area of ​​the surface portion 411 (e.g., the area of ​​the shaded area shown in Figure 12 ) can be located in the compacted region 3211. That is, at least 50% (inclusive) of the area of ​​the surface portion 411 can be located in the compacted region 3211. Thus, since the connection portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, the inner portion 412 can extend from the surface portion 411 toward the conductive portion 20. When at least a majority of the area of ​​the surface portion 411 falls within the compacted region 3211, the volume of the inner portion 412 within the compacted region 3211 is increased. Because there is little or no interlayer gap between the multiple layers of tab sheets 320 within the compacted region 3211, pores caused by interlayer gaps are less likely to form in the molten pool of the compacted region 3211. This helps reduce pores formed in the inner portion 412, thereby improving the flow capacity of the connection portion 4.

[0178] In some embodiments of the present application, referring to Figures 7 and 12 , at least a majority of the contour line 4x of the surface portion 411 (e.g., the contour line of the shaded area shown in Figure 12 , such as the rectangular frame formed by the two long sides 4x1 and the two short sides 4x2) falls within the compacted region 3211. That is, at least 50% (including 50%) of the contour line 4x of the surface portion 411 falls within the compacted region 3211. Therefore, by ensuring that at least a majority of the contour line 4x of the surface portion 411 falls within the compacted region 3211, the problem of thermal cracking in the weld profile of the connecting portion 4 falling on the surface of the gathered portion 321 can be effectively addressed. In addition, since the connecting portion 4 extends from the outer surface of the gathering portion 321 toward the conductive portion 20, the contour line 4y of the internal portion 412 can be extended from the contour line 4x of the surface portion 411 toward the conductive portion 20. When at least most of the contour line 4x of the surface portion 411 falls in the compacted area 3211, it is beneficial to increase the proportion of the contour line 4y of the internal portion 412 falling in the compacted area 3211 relative to the proportion falling in the fluffy area 3212, thereby helping to improve the problem of thermal cracks in the contour line of the first part 41 of the connecting portion 4 formed in the gathering portion 321 as a whole.

[0179] In some embodiments of the present application, referring to Figures 7 and 12 , when at least 60% of the contour line 4x of the surface portion 411 falls within the compacted region 3211, the problem of thermal cracking in the weld profile of the connecting portion 4 on the surface of the gathered portion 321 can be further alleviated. Furthermore, because the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, the contour line 4y of the inner portion 412 can extend from the contour line 4x of the surface portion 411 toward the conductive portion 20. When at least 60% of the contour line 4x of the surface portion 411 falls within the compacted region 3211, the proportion of the contour line 4y of the inner portion 412 falling within the compacted region 3211 relative to the contour line 4y of the fluffy region 3212 can be further increased, thereby further alleviating the problem of thermal cracking in the contour line of the first portion 41 of the connecting portion 4 formed in the gathered portion 321.

[0180] In some embodiments of the present application, in combination with Figure 12, the surface of the gathering portion 321 is long and narrow, and the surface portion 411 is long and narrow and matches the length direction of the gathering portion 321, that is, the length direction of the surface portion 411 is consistent with the length direction of the gathering portion 321. For example, the fourth direction E shown in Figure 12 is the length direction of the gathering portion 321, and at least most of each of the two long sides 4x1 of the surface portion 411 is located in the compacted area 3211, that is, more than 50% (including 50%) of the length of each long side 4x1 is located in the compacted area 3211.

[0181] Therefore, the surface portion 411 can make full use of the space of the gathered portion 321, increase the area of ​​the surface portion 411, and improve the current flow capacity. Moreover, by setting at least most of each long side 4x1 to be located in the compacted area 3211, it is beneficial to increase the portion of the contour line 4x of the surface portion 411 falling in the compacted area 3211, improve the contour thermal crack problem of the surface portion 411, and improve the conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20, thereby improving the reliability of the battery cell 102.

[0182] In some embodiments, referring to Figures 12 and 13 , the compacted region 3211 includes a first sub-region Z1. The first sub-region Z1 is elongated and matches the length and width of the gathered portion 321. Specifically, the length of the first sub-region Z1 coincides with the length of the gathered portion 321, for example, the fourth direction E shown in Figure 13 corresponds to the length of the gathered portion 321. The width of the first sub-region Z1 coincides with the width of the gathered portion 321, for example, the fifth direction F shown in Figure 13 corresponds to the width of the gathered portion 321. A length M1 of the first sub-region Z1 exceeds half the length M of the gathered portion 321, for example, the ratio of the length M1 of the first sub-region Z1 to the length M of the gathered portion 321 is greater than 50%. There are two first sub-regions Z1, spaced apart along the width of the gathered portion 321. The two long sides 4x1 of the surface portion 411 are respectively located in the two first sub-regions Z1 , that is, one long side 4x1 is located in one of the first sub-regions Z1 , and the other long side 4x1 is located in the other first sub-region Z1 .

[0183] Thus, by configuring the compacted region 3211 to include the two first sub-regions Z1, and locating the two long sides (4x1) of the surface portion 411 of the connecting portion 4 within the two first sub-regions Z1, the length of the first sub-regions Z1 is increased, and the majority of the contour of the surface portion 411 can fully utilize the compacted region 3211. This further increases the portion of the contour line 4x of the surface portion 411 that falls within the compacted region 3211, thereby further alleviating the risk of thermal cracking within the contour of the surface portion 411, further improving the conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20, and thereby enhancing the reliability of the battery cell 102. Furthermore, as the inner portion 412 extends from the surface portion 411 toward the conductive portion 20, the majority of the inner portion 412 can also fall within the first sub-region Z1, thereby increasing the volume of the inner portion 412 within the compacted region 3211, further alleviating the risk of air holes within the inner portion 412, and further improving the current carrying capacity.

[0184] For example, the width M2 of the first sub-region Z1 (the minimum width of the first sub-region Z1) exceeds one-fifth of the width M of the gathered portion 321. Thus, the first sub-region Z1 accounts for a larger area than the gathered portion 321, facilitating full utilization of the gathered portion 321 for laser welding with the conductive portion 20. This allows the contour of the laser weld to fall more within the compacted region 3211, thereby improving the electrical conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20.

[0185] In some embodiments, with reference to FIG13 , each long side of a first sub-region Z1 has a plurality of protruding segments Z11 spaced apart along the length of the gathered portion 321, with the protruding segments Z11 protruding in the width direction of the gathered portion 321. That is, a long side of each first sub-region Z1 that is away from another first sub-region Z1 has a protruding segment Z11 that protrudes away from the other first sub-region Z1, with multiple protruding segments Z11 on that long side spaced apart along the length of that long side. Simultaneously, a long side of each first sub-region Z1 that is close to another first sub-region Z1 has a plurality of protruding segments Z11 that protrudes toward the other first sub-region Z1, with multiple protruding segments Z11 on that long side spaced apart along the length of that long side.

[0186] Therefore, each long side of the first sub-area Z1 is uneven, which helps to improve the grip during welding and provide greater friction, so that the first sub-area Z1 can be effectively compacted and the compaction rate of the first sub-area Z1 is improved. In this way, when part of the contour line of the laser weld falls on the first sub-area Z1, the problem of thermal cracks in this part of the contour line can be further improved.

[0187] In some embodiments, referring to FIG13 , the compacted region 3211 includes a plurality of second sub-regions Z2 disposed between two first sub-regions Z1 and spaced apart along the length of the gathered portion 321. That is, the compacted region 3211 includes a plurality of second sub-regions Z2 spaced apart along the length of the gathered portion 321. In the width direction of the gathered portion 321, the plurality of second sub-regions Z2 are located between the two first sub-regions Z1. Referring to FIG13 , the protruding segments Z11 on the sides of the two first sub-regions Z1 adjacent to each other are positioned opposite each other, and two opposing protruding segments Z11 are disposed between each pair of adjacent second sub-regions Z2. That is, the non-protruding portions on the sides of the two first sub-regions Z1 adjacent to each other are also positioned opposite each other. The second sub-regions Z2 are arranged at opposing and non-protruding portions, so that the plurality of second sub-regions Z2 and the plurality of protruding segments Z11 are alternately disposed along the length of the gathered portion 321.

[0188] Therefore, the space of the gathered portion 321 can be further utilized to construct the compacted area 3211. When the two long sides 4x1 of the surface portion 411 are respectively located in the two first sub-areas Z1, the surface portion 411 can cover at least part of the second sub-area Z2, thereby facilitating increasing the portion of the laser weld falling in the compacted area 3211, further improving the problem of pores appearing in the molten pool of the laser weld, and further improving the flow capacity.

[0189] In some embodiments, in combination with Figure 13, the gathering portion 321 includes a fluffy area 3212, and the fluffy area 3212 includes a first fluffy area L1 located between the two first sub-areas Z1, and separated between the two first sub-areas Z1 and between the first sub-area Z1 and the second sub-area Z2. The first fluffy area L1 is in the form of a line on the outer surface of the gathering portion 321 so that the outline of the second sub-area Z2 matches the outline of the first sub-area Z1.

[0190] In the above technical solution, the first fluffy area L1 in the form of a line is set to separate the two first sub-areas Z1, and to separate the first sub-area Z1 and the second sub-area Z2, so that the contour of the second sub-area Z2 matches the contours of the two first sub-areas Z1, that is, the protruding position of the contour of the first sub-area Z1 corresponds to the concave position of the contour of the second sub-area Z2, the distance between the two first sub-areas Z1 is small, and the distance between the first sub-area Z1 and the second sub-area Z2 is small, so that most of the area where the molten pool of the laser weld is located is the compacted area 3211, which is beneficial to improve the problem of pores in the molten pool of the laser weld and further improve the flow capacity.

[0191] For example, on the outer surface of the gathered portion 321, the width of the first fluffy area L1 in the form of a line can be only 0.2mm-0.6mm, so that the distance between the two first sub-areas Z1 is smaller, and the distance between the first sub-area Z1 and the second sub-area Z2 is smaller, which is beneficial for the area where the molten pool of the laser weld is located to be mostly the compacted area 3211, thereby helping to improve the problem of pores in the molten pool of the laser weld and further improve the flow capacity.

[0192] In some embodiments, referring to FIG13 , the compacted area 3211 includes a plurality of third sub-areas Z3, which are spaced apart and arranged around two first sub-areas Z1. That is, each first sub-area Z1 has a third sub-area Z3 on both sides of the converged portion 321 in the length direction, and each first sub-area Z1 also has a third sub-area Z3 on the side of the converged portion 321 in the width direction away from the other first sub-area Z1.

[0193] Therefore, by setting up multiple third sub-areas Z3 around the two first sub-areas Z1, it helps to improve the grip during welding to provide greater friction, so that the first sub-area Z1 can be effectively compacted and the compaction rate of the first sub-area Z1 can be improved. In this way, when part of the contour line of the laser weld falls on the first sub-area Z1, the problem of thermal cracks in this part of the contour line can be further improved.

[0194] In some embodiments, in combination with Figure 13, the gathering portion 321 includes a fluffy area 3212, the fluffy area 3212 includes a second fluffy area L2 arranged on the periphery of the two first sub-areas Z1, and separated between the first sub-area Z1 and the third sub-area Z3 and between the two adjacent third sub-areas Z3, and the second fluffy area L2 is in the form of a line on the outer surface of the gathering portion 321 so that the outline of the third sub-area Z3 matches the outline of the first sub-area Z1.

[0195] For example, the long side of the first sub-region Z1 is concave-convex, and the multiple third sub-regions Z3 arranged on the long side of the first sub-region Z1 can be divided into region 1 Z31 and region 2 Z32 alternately arranged along the length direction of the gathering portion 321. The area of ​​region 1 Z31 is relatively large and is opposite to the non-protruding position of the long side of the first sub-region Z1, and the area of ​​region 2 Z32 is relatively small and is opposite to the protruding section Z11 of the long side of the first sub-region Z1, so that the outline of the third sub-region Z3 can match the outline of the first sub-region Z1.

[0196] In the above technical solution, a second fluffy area L2 in the form of a line is set to separate the first sub-area Z1 and the third sub-area Z3, and to separate the adjacent third sub-area Z3, so that the contour of the third sub-area Z3 matches the contour of the first sub-area Z1, that is, the protruding position of the contour of the first sub-area Z1 corresponds to the recessed position of the contour of the third sub-area Z3, the spacing between adjacent third sub-areas Z3 is small, and the spacing between the first sub-area Z1 and the third sub-area Z3 is small, so that the spatial structure compaction area 3211 of the gathering portion 321 can be more fully utilized to enhance the grip during welding, to provide greater friction, and to enhance the compaction rate of the first sub-area Z1. In this way, when part of the contour line of the laser weld falls on the first sub-area Z1, the problem of thermal cracks in this part of the contour line can be further improved.

[0197] For example, on the outer surface of the gathering portion 321, the width of the second fluffy area L2 in the form of a line can be only 0.2mm-0.6mm, so that the distance between adjacent third sub-areas Z3 is smaller, and the distance between the first sub-area Z1 and the third sub-area Z3 is smaller, which is conducive to improving the grip during welding, so as to provide greater friction and further improve the compaction rate of the first sub-area Z1.

[0198] In some other embodiments of the present application, referring to Figure 14, the compaction area 3211 includes a plurality of first compaction rows Z4 spaced apart along the width direction of the gathering portion 321 (for example, the fifth direction F shown in Figure 14), and each first compaction row Z4 includes a plurality of fourth sub-areas Z5 spaced apart along the length direction of the gathering portion 321 (for example, the fourth direction E shown in Figure 14), and the two long sides 4x1 of the surface portion 411 are respectively arranged corresponding to two of the first compaction rows Z4, and each long side 4x1 passes through the plurality of fourth sub-areas Z5 in the corresponding first compaction row Z4, and the size M2 of the fourth sub-area Z5 in the length direction of the gathering portion 321 is greater than the spacing M3 between the two adjacent fourth sub-areas Z5 in the length direction of the gathering portion 321.

[0199] Exemplarily, referring to Figure 14, the gathering portion 321 includes a fluffy area 3212, and the fluffy area 3212 includes a third fluffy zone L3 separated between two adjacent fourth sub-areas Z5 in the same first compaction row Z4. The third fluffy zone L3 is in the form of a line extending along the width direction of the gathering portion 321 (for example, the fifth direction F shown in Figure 14) on the outer surface of the gathering portion 321, and the dimension M2 of the fourth sub-area Z5 in the length direction of the gathering portion 321 (for example, the fourth direction E shown in Figure 14) is greater than the width M3 of the fourth fluffy zone L4 in the length direction of the gathering portion 321 (for example, the fourth direction E shown in Figure 14).

[0200] Therefore, by setting the compacted area 3211 to include multiple fourth sub-areas Z5 in the above-mentioned arrangement form, setting the size M2 of the fourth sub-area Z5 in the length direction of the gathering portion 321 to be larger than the spacing M3 between two adjacent fourth sub-areas Z5 in the length direction of the gathering portion 321, the two long sides 4x1 of the surface portion 411 of the connecting portion 4 are respectively arranged corresponding to the two first compacted rows Z4, and each long side 4x1 passes through the multiple fourth sub-areas Z5 in the corresponding first compacted row Z4, so that most of the contour of the surface portion 411 can make full use of the compacted area 3211, so that the contour line 4x of the surface portion 411 falls in the compacted area 3211. The part is increased, the problem of thermal cracks in the contour of the surface portion 411 is improved, the conductivity yield and connection strength between the gathering portion 321 and the conductive portion 20 are improved, and the reliability of the battery cell 102 is improved. Moreover, when the internal part 412 extends from the surface part 411 toward the conductive part 20, most of the internal part 412 can also fall into the fourth sub-area Z5, which is conducive to increasing the volume of the internal part 412 falling in the compacted area 3211, so as to further improve the problem of air holes in the internal part 412, and further improve the flow capacity.

[0201] Exemplarily, referring to Figure 14, there are two first compaction rows Z4, the fourth sub-region Z5 is long and narrow, and the length direction of the fourth sub-region Z5 (for example, the fifth direction F shown in Figure 14) matches the width direction of the gathering portion 321, the width direction of the fourth sub-region Z5 (for example, the fourth direction E shown in Figure 14) matches the length direction of the gathering portion 321, and the length N2 of the fourth sub-region Z5 exceeds one-quarter of the width N of the gathering portion 321.

[0202] Therefore, the fourth sub-region Z5 can make full use of the space of the gathering portion 321, and the area of ​​the fourth sub-region Z5 is relatively large. When the contour line of the laser weld passes through multiple fourth sub-regions Z5, it is beneficial to improve the problem of thermal cracks in the contour line of the laser weld and improve the problem of pores in the molten pool of the laser weld, thereby improving the conductive yield and connection strength between the gathering portion 321 and the conductive portion 20.

[0203] Exemplarily, referring to Figure 14, the gathering portion 321 includes a fluffy area 3212, the fluffy area 3212 includes a third fluffy zone L3 separated between two adjacent fourth sub-areas Z5 in the same first compaction row Z4, and a fourth fluffy zone L4 separated between two adjacent first compaction rows Z4, the third fluffy zone L3 is in the form of a line extending along the width direction of the gathering portion 321 on the outer surface of the gathering portion 321, and the fourth fluffy zone L4 is in the form of a line extending along the length direction of the gathering portion 321 on the outer surface of the gathering portion 321, and the width M3 of the third fluffy zone L3 is smaller than the width M4 of the fourth fluffy zone L4.

[0204] This helps reduce the length of the long side 4x1 of the surface portion 411 that falls within the third fluffy zone L3, further improving the risk of thermal cracking along the contour of the surface portion 411. Furthermore, since both the third and fourth fluffy zones L3 and L4 appear as lines on the outer surface of the gathered portion 321, this helps increase the proportion of the fourth sub-region Z5 relative to the gathered portion 321, and thus increases the proportion of the compacted region 3211 relative to the gathered portion 321. This reduces the risk of thermal cracking along the contour of the laser weld when the contour passes through multiple fourth sub-regions Z5, further improving the risk of porosity within the molten pool, and thus enhancing flow capacity.

[0205] Exemplarily, the shape of the fourth sub-region Z5 is not limited, for example, it can be rectangular, circular, etc. When processed into a rectangle, it is convenient for the design of the welding head 400, and it is beneficial to increase the proportion of the compacted area 3211, so that the surface part 411 falls more into the fourth sub-region Z5.

[0206] 15 , the entire surface portion 411 is located in the compacted region 3211 . In other words, the surface portion 411 is completely located in the compacted region 3211 , with no portion located in the fluffy region 3212 .

[0207] As a result, the entire contour of the surface portion 411 is less susceptible to thermal cracking, effectively improving the conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20, and enhancing the reliability of the battery cell 102. Furthermore, because the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, when the surface portion 411 is entirely within the compacted region 3211, if the inner portion 412 extends and gradually tapers along the thickness of the gathered portion 321 from the surface portion 411 toward the conductive portion 20, the inner portion 412 can also be entirely within the compacted region 3211. This makes the contour of the inner portion 412 less susceptible to thermal cracking, further improving the conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20, and enhancing the reliability of the battery cell 102. Furthermore, the inner portion 412 is less susceptible to air holes, further improving current carrying capacity.

[0208] In some embodiments, referring to FIG. 15 , the compacted region 3211 includes a plurality of spaced-apart fifth sub-regions Z6, and the surface portions 411 are spaced-apart and correspond one-to-one to the plurality of fifth sub-regions Z6. For example, a pulsed laser may be used to weld each fifth sub-region Z6, so that each fifth sub-region Z6 has a surface portion 411 of the connecting portion 4.

[0209] For example, when the tab 320 is aluminum foil, the thermal expansion coefficient of aluminum is large. The greater the heat input during laser welding, the more serious the thermal cracks of the aluminum tab will be. Laser welding can be performed using a pulsed laser with low heat input. The laser welding position falls on the compacted area 3211, which can improve the problem of thermal cracks in the contour of the laser weld.

[0210] Therefore, by setting the compacted area 3211 to include multiple fifth sub-areas Z6 arranged at intervals, and setting multiple surface parts 411 to multiple fifth sub-areas Z6 in a one-to-one correspondence, it can be simply and effectively achieved that the surface part 411 is located in the compacted area 3211 as a whole, and the total area of ​​the surface parts 411 added together is relatively large, meeting the current capacity requirements. Moreover, if the internal part 412 extends and gradually shrinks along the thickness direction of the gathering part 321 from the surface part 411 to the conductive part 20, the internal parts 412 extending from each surface part 411 can also fall in the fifth sub-area Z6 respectively, so that the contour of the internal part 412 is not prone to thermal cracks, and the internal part 412 is not prone to pores, which is beneficial to improving the conductivity yield and connection strength between the gathering part 321 and the conductive part 20, improving the current capacity, and improving the reliability of the battery cell 102.

[0211] In some embodiments, with reference to FIG15 , the compacted region 3211 includes a plurality of second compacted rows Z7 spaced apart along the width direction of the gathered portion 321 (e.g., the fifth direction F shown in FIG15 ), and each second compacted row Z7 includes a plurality of fifth sub-regions Z6 spaced apart along the length direction of the gathered portion 321 (e.g., the fourth direction E shown in FIG15 ). Thus, by configuring the compacted region 3211 to include a plurality of fifth sub-regions Z6 arranged in the above-described manner, the arrangement of the fifth sub-regions Z6 can be simplified, making it easier to locate each fifth sub-region Z6 for separate laser welding. Furthermore, this helps simplify the design of the compacted region 3211, making the gathered portion 321 easier to machine, and reducing the design and machining difficulty of the welding head used to machine the gathered portion 321.

[0212] For example, referring to FIG15 , the gathered portion 321 includes a fluffy area 3212, which includes a fifth fluffy area L5 separated between two adjacent fifth sub-areas Z6 in the same second compacted row Z7, and a sixth fluffy area L6 separated between two adjacent second compacted rows Z7. The fifth fluffy area L5 is formed as a line extending along the width of the gathered portion 321 on the outer surface of the gathered portion 321, and the sixth fluffy area L6 is formed as a line extending along the length of the gathered portion 321 on the outer surface of the gathered portion 321. The width M5 of the fifth fluffy area L5 is smaller than the dimension M6 of the fifth sub-area Z6 along the length of the gathered portion 321 (e.g., the fourth direction E shown in FIG15 ), and the width M7 of the sixth fluffy area L6 is smaller than the dimension N3 of the fifth sub-area Z6 along the width of the gathered portion 321 (e.g., the fifth direction F shown in FIG15 ). This helps to increase the area of ​​each fifth sub-area Z6, thereby increasing the proportion of the compacted region 3211.

[0213] In some embodiments, in combination with Figure 15, there are two second compaction rows Z7, and the dimension N3 of the fifth sub-region Z6 in the width direction of the gathering portion 321 (for example, the fifth direction F shown in Figure 15) and the dimension M6 in the length direction of the gathering portion 321 (for example, the fourth direction E shown in Figure 15) both exceed one-quarter of the width N of the gathering portion 321.

[0214] Therefore, by setting the number of the second compaction rows Z7 to two, and setting the fifth sub-area Z6 so that the dimension N3 in the width direction of the gathering portion 321 and the dimension M6 in the length direction of the gathering portion 321 are both greater than one quarter of the width N of the gathering portion 321, the area of ​​each fifth sub-area Z6 is relatively large, which is beneficial to reducing the number of fifth sub-areas Z6, reducing the number of welding times, and making the area of ​​each surface portion 411 relatively large, which is convenient for processing and improves the flow capacity.

[0215] Exemplarily, the shape of the fifth sub-region Z6 is not limited, for example, it can be rectangular, circular, etc. When processed into a rectangle, it is convenient for the design of the welding head 400, which is beneficial to increase the area of ​​each fifth sub-region Z6, and thereby increase the proportion of the compacted area 3211.

[0216] In some embodiments of the present application, in combination with Figure 10, the connecting portion 4 includes a first connecting portion 4a and a second connecting portion 4b, the second connecting portion 4b extends into the conductive portion 20, the extension depth G1 of the first connecting portion 4a is less than the extension depth G2 of the second connecting portion 4b, the surface portion 411 includes a first surface portion 4a1 of the first connecting portion 4a formed on the outer surface of the convergent portion 321, and a second surface portion 4b1 of the second connecting portion 4b formed on the outer surface of the convergent portion 321, and at least most of the contour line of the second surface portion 4b1 is located within the first surface portion 4a1.

[0217] Since the connecting portion 4 extends from the outer surface of the gathering portion 321 toward the conductive portion 20, and the connecting portion 4 includes a first connecting portion 4a and a second connecting portion 4b, the first connecting portion 4a extends from the outer surface of the gathering portion 321 toward the conductive portion 20, so that the first connecting portion 4a includes a first surface portion 4a1 formed on the outer surface of the gathering portion 321, and the second connecting portion 4b also extends from the outer surface of the gathering portion 321 toward the conductive portion 20, so that the second connecting portion 4b includes a second surface portion 4b1 formed on the outer surface of the gathering portion 321.

[0218] For example, with reference to FIG11 , the connection portion 4 includes only the first connection portion 4a and the second connection portion 4b, so that the connection portion 4 is composed of the first connection portion 4a and the second connection portion 4b, and the surface portion 411 is composed of the first face portion 4a1 and the second face portion 4b1. However, the present application is not limited thereto, and the connection portion 4 may also include other portions in addition to the first connection portion 4a and the second connection portion 4b. For example, with reference to FIG10 , the connection portion 4 may further include a third connection portion 4c.

[0219] When the connecting portion 4 extends along the thickness direction of the gathered portion 321, the extended depth is the depth in the thickness direction of the gathered portion 321 (e.g., the third direction Z shown in FIG10 ). If the connecting portion 4 extends along a direction oblique to the thickness direction of the gathered portion 321, the extended depth is the depth along the oblique direction. To simplify the description, the following description uses the extended depth as the depth in the thickness direction of the gathered portion 321 as an example.

[0220] In the above technical solution, because the extension depth G2 of the second connecting portion 4b is greater than the extension depth G1 of the first connecting portion 4a, the second connecting portion 4b can extend into the conductive portion 20. As a result, a portion of the second connecting portion 4b is formed in the gathered portion 321, and the remaining portion is formed in the conductive portion 20. The second connecting portion 4b can serve to connect the gathered portion 321 and the conductive portion 20. Furthermore, because the extension depth G1 of the first connecting portion 4a is less than the extension depth G2 of the second connecting portion 4b, less energy is required to weld the first connecting portion 4a during laser welding, and the profile of the first connecting portion 4a is less susceptible to thermal cracking. And since at least most of the contour line of the second face 4b1 is located within the first face 4a1, more than 50% (including 50%) of the contour line of the second face 4b1 on the outer surface of the gathering portion 321 can fall within the first face 4a1, thereby improving the problem of thermal cracks in the contour line of the second face 4b1, and at least part of the contour line of the molten pool formed by the second connecting portion 4b can also be located within the first connecting portion 4a, which is beneficial to improving the problem of thermal cracks in the contour of the molten pool of the second connecting portion 4b, and improving the conductivity yield and connection strength between the conductive portion 20 and the gathering portion 321.

[0221] For example, during laser welding, the first connection part 4a can be obtained by laser welding first, and the first connection part 4a is used as a base weld, and then the second connection part 4b is obtained by laser welding, and the second connection part 4b is used as a main weld. The extension depth of the main weld is greater than the extension depth of the base weld, and at least part of the contour of the main weld is located within the base weld, which is conducive to improving the problem of thermal cracks in the contours of the base weld and the main weld.

[0222] In some embodiments of the present application, the shape of the first surface 4a1 matches the outline of the second surface 4b1, with at least a portion of the outline of the second surface 4b1 falling within the center of the first surface 4a1. The first surface 4a1 may extend partially or entirely along the outline of the second surface 4b1 to ensure that the shape of the first surface 4a1 matches the outline of the second surface 4b1. Furthermore, in the embodiments of the present application, the term "center" is used broadly to refer to the exact center or near the exact center, i.e., the minimum distance from the exact center is less than the minimum distance from the outline.

[0223] Therefore, by setting the shape of the first face 4a1 to match the contour line shape of the second face 4b1, it is beneficial to make the contour line of the second face 4b1 fall more within the first face 4a1, thereby helping to further improve the problem of thermal cracks in the contour line of the second face 4b1. Furthermore, when laser welding is performed, the first connection part 4a and the second connection part 4b can respectively present a shape that extends and gradually shrinks along the thickness direction of the convergence part 321 as a whole. By setting at least most of the contour line of the second face 4b1 in the central position of the first face 4a1, it is beneficial for the molten pool contour of the second connection part 4b to extend to the convergence part 321 to fall more within the first connection part 4a, thereby helping to further improve the problem of thermal cracks in the contour of the second connection part 4b.

[0224] In some embodiments, in combination with Figures 14, 16-18, the surface of the gathering portion 321 can be an elongated strip, the surface portion 411 is an elongated strip and matches the length direction of the gathering portion 321, the first face portion 4a1 is an elongated strip extending along the length direction of the gathering portion 321, and two are arranged at intervals along the width direction of the gathering portion 321, the second face portion 4b1 is an elongated strip extending along the length direction of the gathering portion 321, and the two long sides of the second face portion 4b1 fall within the two first face portions 4a1 respectively, so that the shape of the first face portion 4a1 matches the contour line shape of the second face portion 4b1, and the contour line of the second face portion 4b1 partially falls within the corresponding first face portion 4a1.

[0225] Thus, one long side of the second face 4b1 can fall within one of the first face parts 4a1, and the other long side of the second face part 4b1 can fall within the other first face part 4a1, so that the two long sides of the second face part 4b1 can be respectively located within the first connecting part 4a, and most of the contour of the second face part 4b1 is not prone to thermal cracks. Moreover, the contour of the molten pool extending from the two long sides of the second face part 4b1 to the convergent part 321 can also be mostly located within the first connecting part 4a, thereby improving the problem of thermal cracks in the contour of the second connecting part 4b and improving the conductive yield and connection strength between the convergent part 321 and the conductive part 20.

[0226] In some embodiments, in combination with Figures 14, 16-18, when the first face 4a1 is a long strip extending along the length direction of the gathering portion 321 and the two first faces 4a1 are spaced apart along the width direction of the gathering portion 321, and the second face 4b1 is a long strip extending along the length direction of the gathering portion 321, and the two long sides of the second face 4b1 fall within the two first faces 4a1 respectively, if the contour line of the second face 4b1 at least mostly falls in the central position of the first face 4a1, it means that the long side of the second face 4b1 extends along the length direction of the first face 4a1 and is located in the central position of the width direction of the first face 4a1. For example, during continuous laser welding, two base welds can be welded first along the length direction of the converged portion 321, and then the main weld can be welded between the two base welds, so that the two long sides of the main weld fall within the two base welds respectively, and the long side of the main weld can fall at the center position of the width of the base weld, which is conducive to the molten pool contour of the main weld falling more into the base weld, thereby improving the problem of thermal cracks in the contour of the main weld.

[0227] For example, when the first surface portion 4a1 is in the shape of an elongated strip, the first connecting portion 4a may be welded using a spiral line, which facilitates processing and helps improve weld quality.

[0228] For example, when the second surface portion 4b1 is in the shape of an elongated strip, the second connecting portion 4b may be welded using a spiral line, which facilitates processing and helps improve weld quality.

[0229] In some embodiments, referring to Figures 15 and 19-21 , a plurality of surface portions 411 are spaced apart. Each surface portion 411 includes a first surface portion 4a1 and a second surface portion 4b1. The first surface portion 4a1 is annular and surrounds the corresponding second surface portion 4b1. The outline of the second surface portion 4b1 is located within the corresponding first surface portion 4a1, so that the shape of the first surface portion 4a1 matches the outline of the second surface portion 4b1. The annular shape can be, but is not limited to, a circular shape. For example, it can also be a polygonal shape, such as a rectangular ring.

[0230] As a result, the contour lines of the second face 4b1 all fall within the corresponding first face 4a1, so that the contour lines of the second face 4b1 are located within the first connecting portion 4a throughout the entire circumference. The contour of the second face 4b1 is not prone to thermal cracks, and the contour of the molten pool extending from the contour of the second face 4b1 to the convergent portion 321 can also be mostly located within the first connecting portion 4a, thereby improving the problem of thermal cracks in the contour of the second connecting portion 4b and improving the conductivity yield and connection strength between the convergent portion 321 and the conductive portion 20.

[0231] In some embodiments, when the first surface 4a1 is annular and surrounds the second surface 4b1, the outline of the second surface 4b1 is located within the first surface 4a1. If at least a majority of the outline of the second surface 4b1 falls within the center of the first surface 4a1, then the outline of the second surface 4b1 extends along the annular trajectory of the first surface 4a1 and is located centrally between the inner and outer rings of the annular first surface 4a1. For example, during pulsed laser welding, multiple annular root welds can be welded first, and then the main weld can be welded within each root weld. This ensures that the outline of the main weld falls within the annular root weld, for example, along the center line of the annular weld. This helps the molten pool outline of the main weld fall more deeply within the root weld, thereby alleviating the risk of thermal cracking along the outline of the main weld.

[0232] In some embodiments of the present application, referring to FIG10 , the extension depth G1 of the first connection portion 4a is 60%-100% of the thickness T1 of the compacted region 3211. Thus, the first connection portion 4a extends from the surface of the gathered portion 321 only into the gathered portion 321, and the extension depth exceeds half the thickness of the compacted region 3211. In this case, the molten pool depth of the first connection portion 4a is not too deep, requiring insufficient energy during welding, and thus reducing the risk of thermal cracking. This helps improve the electrical conductivity yield and connection strength between the gathered portion 321 and the conductive portion 20. Furthermore, the molten pool depth of the first connection portion 4a is not too small, allowing the contour of the second connection portion 4b to fit more deeply into the first connection portion 4a, thereby alleviating the risk of thermal cracking in the contour of the second connection portion 4b.

[0233] In some embodiments of the present application, referring to Figure 10, the connecting portion 4 also includes a third connecting portion 4c, the extension depth G3 of the third connecting portion 4c is less than the extension depth G1 of the first connecting portion 4a, the third connecting portion 4c is arranged on the side of the first connecting portion 4a away from the second connecting portion 4b, and the surface portion 411 also includes a third surface portion 4c1 formed by the third connecting portion 4c on the outer surface of the gathering portion 321, and at least part of the contour line of the first surface portion 4a1 is located within the third surface portion 4c1.

[0234] Since the connection portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20 and includes the third connection portion 4c, the third connection portion 4c extends from the outer surface of the gathered portion 321 toward the conductive portion 20, and thus the third connection portion 4c includes a third surface portion 4c1 formed on the outer surface of the gathered portion 321. Exemplarily, the connection portion 4 includes only the first connection portion 4a, the second connection portion 4b, and the third connection portion 4c, so that the connection portion 4 is composed of the first connection portion 4a, the second connection portion 4b, and the third connection portion 4c, and the surface portion 411 is composed of the first surface portion 4a1, the second surface portion 4b1, and the third surface portion 4c1. However, the present application is not limited to this, and the connection portion 4 may also include other portions in addition to the first connection portion 4a, the second connection portion 4b, and the third connection portion 4c.

[0235] In the above technical solution, because the extended depth G3 of the third connecting portion 4c is less than the extended depth G1 of the first connecting portion 4a, the energy required for laser welding of the third connecting portion 4c is less, making the contour of the third connecting portion 4c less susceptible to thermal cracking. Furthermore, because the third connecting portion 4c is located on the side of the first connecting portion 4a away from the second connecting portion 4b, at least a portion of the contour of the first surface portion 4a1 lies within the third surface portion 4c1, thereby alleviating the risk of thermal cracking of the contour of the first surface portion 4a1. Furthermore, at least a portion of the contour of the molten pool formed by the first connecting portion 4a can also lie within the third connecting portion 4c, thereby alleviating the risk of thermal cracking of the contour of the molten pool of the first connecting portion 4a and improving the electrical conductivity yield and connection strength between the conductive portion 20 and the convergent portion 321.

[0236] For example, during laser welding, the first connection part 4a can be obtained by laser welding first, and the first connection part 4a is used as a base weld. Then, the second connection part 4b can be obtained by laser welding, and the second connection part 4b is used as a main weld. The extension depth G2 of the main weld is greater than the extension depth G1 of the base weld, and at least part of the contour line of the main weld is located within the base weld, which is beneficial to improving the problem of thermal cracks in the contours of the base weld and the main weld. Thereafter, the third connection part 4c is obtained by laser welding, and the third connection part 4c is used as a repair weld. The extension depth G3 of the repair weld is less than the extension depth G1 of the base weld, and at least part of the contour line of the base weld falls within the repair weld, which is beneficial to improving the problem of thermal cracks in the contours of the base weld and the repair weld.

[0237] The repair weld may repair the entire contour of the bottom weld or only a portion of the contour of the bottom weld, depending on the actual situation. For example, in some embodiments, at least a majority of the contour of the first surface portion 4a1 lies within the third surface portion 4c1. Thus, at least 50% (including 50%) of the contour of the first surface portion 4a1 can be repaired by the third connecting portion 4c, thereby more effectively alleviating the problem of thermal cracking of the contour of the first surface portion 4a1.

[0238] In some embodiments of the present application, the shape of the third surface portion 4c1 matches the outline of the first surface portion 4a1, with at least a majority of the outline of the first surface portion 4a1 falling within the center of the third surface portion 4c1. The third surface portion 4c1 may extend partially or entirely along the outline of the first surface portion 4a1, such that the shape of the third surface portion 4c1 matches the outline of the first surface portion 4a1. For example, the first surface portion 4a1 may be in the shape of an elongated strip, and the third surface portion 4c1 may be in the shape of an elongated strip extending along the length of the first surface portion 4a1, with the long side of the first surface portion 4a1 located at the center of the width of the third surface portion 4c1. Alternatively, the first surface portion 4a1 may be in the shape of a ring, and the third surface portion 4c1 may be in the shape of a ring surrounding the first surface portion 4a1, with the outer ring of the first surface portion 4a1 located at the center between the inner and outer rings of the third surface portion 4c1.

[0239] Therefore, by setting the shape of the third face 4c1 to match the contour line shape of the first face 4a1, it is beneficial to make the contour line of the first face 4a1 fall more within the third face 4c1, which is beneficial to further improve the problem of thermal cracks in the contour line of the first face 4a1. Furthermore, when laser welding is performed, the first connection part 4a and the third connection part 4c can respectively present a shape that extends and gradually shrinks along the thickness direction of the convergence part 321 as a whole. By setting the contour line of the first face 4a1 at least for the most part in the central position of the third face 4c1, it is beneficial for the molten pool contour of the first connection part 4a extending to the convergence part 321 to fall more within the third connection part 4c, which is beneficial to further improve the problem of thermal cracks in the contour of the first connection part 4a.

[0240] For example, when the third surface portion 4c1 is in the shape of an elongated strip, the third connecting portion 4c may be welded using a spiral line, thereby facilitating processing and improving weld quality.

[0241] In some embodiments of the present application, referring to FIG. 10 , the extended depth G3 of the third connecting portion 4c is 20%-60% of the thickness T1 of the compacted region 3211. Thus, the third connecting portion 4c extends only from the surface of the converged portion 321 into the converged portion 321, and the molten pool depth of the third connecting portion 4c is relatively small. This reduces the need for excessive energy during welding, making thermal cracking less likely to occur in the contour, thereby improving the electrical conductivity yield and connection strength between the converged portion 321 and the conductive portion 20. Furthermore, the molten pool depth of the third connecting portion 4c is not too small, allowing the contour of the first connecting portion 4a to fall further into the third connecting portion 4c, thereby alleviating the risk of thermal cracking in the contour of the first connecting portion 4a.

[0242] For example, with reference to FIG10 , laser welds include a base weld, a main weld, and a repair weld. The base weld is welded first, and the penetration depth G1 of the base weld is 60% to 120% of the thickness T1 of the compacted area. For example, the penetration depth G1 of the base weld can be equal to the thickness T1 of the compacted area. The main welds are welded in the second batch. While the main welds meet the flow area and welding process requirements, it is necessary to ensure that the outline of the main weld falls in the center of the base weld. The repair welds are welded in the third batch. The center of the repair weld is located at the outline of the base weld, and the penetration depth G3 of the repair weld is 20% to 60% of the thickness T1 of the compacted area. The molten pool outline of the base weld has no thermal cracks, and 60% to 100% of the outline of the molten pool after the base weld and the main weld are fused is in the compacted area.

[0243] Regardless of whether the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20 or from the conductive portion 20 toward the outer surface of the gathered portion 321, the connecting portion 4 includes an inner portion 412 formed within the gathered portion 321. In some embodiments of the present application, with reference to FIG7 , at least a majority of the contour line 4y of the inner portion 412 may be located within the compacted region 3211. That is, at least 50% (including 50%) of the contour line of the portion of the connecting portion 4 formed within the gathered portion 321 may be located within the compacted region 3211. For example, the contour line of the portion of the connecting portion 4 formed within the gathered portion 321 may be entirely located within the compacted region 3211. For another example, a portion of the contour line of the portion of the connecting portion 4 formed within the gathered portion 321 may fall within the compacted region 3211, while the remainder may fall within the fluffy region 3212, with the portion falling within the compacted region 3211 accounting for a greater proportion than the portion falling within the fluffy region 3212.

[0244] In this way, in the above technical solution, since at least most of the contour line of the portion of the connecting portion 4 formed in the gathered portion 321 is set in the compacted area 3211, the multi-layer pole tab sheets 320 in the compacted area 3211 are very tightly combined together with no or almost no interlayer gaps, thereby improving the problem of thermal cracks in the contour of the weld caused by the interlayer gaps, thereby improving the conductive yield and connection strength between the pole tab portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0245] In some embodiments of the present application, more than 60% (including 60%) of the contour line 4y of the inner portion 412 falls within the compacted region 3211. Therefore, by setting more than 60% of the contour line 4y of the inner portion 412 to fall within the compacted region 3211, it is helpful to further improve the problem of thermal cracks occurring in the molten pool contour of the connecting portion 4 falling within the convergent portion 321. In addition, when the connecting portion 4 extends from the outer surface of the gathered portion 321 toward the conductive portion 20, most of the contour line of the first portion 41 is the contour line 4y of the internal portion 412. When more than 60% of the contour line 4y of the internal portion 412 falls in the compacted area 3211, it is beneficial to increase the proportion of the contour line of the first portion 41 that falls in the compacted area 3211 relative to the proportion that falls in the fluffy area 3212. This can improve the problem of thermal cracks in the contour line of the first portion 41 of the connecting portion 4 formed in the gathered portion 321 as a whole, further improve the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improve the reliability of the battery cell 102.

[0246] In some embodiments of the present application, when the connecting portion 4 extends from the outer surface of the gathering portion 321 toward the conductive portion 20, more than 60% of the contour line 4x of the surface portion 411 falls in the compacted area 3211, and more than 60% of the contour line 4y of the internal portion 412 also falls in the compacted area 3211, it is beneficial to further increase the proportion of the contour line of the first portion 41 falling in the compacted area 3211 relative to the proportion falling in the fluffy area 3212, which can improve the problem of thermal cracks in the contour line of the first portion 41 of the connecting portion 4 formed in the gathering portion 321 as a whole.

[0247] In some embodiments of the present application, referring to FIG. 7 , at least a majority of the volume of the inner portion 412 falls within the compacted region 3211. That is, more than 50% (including 50%) of the volume of the inner portion 412 is located within the compacted region 3211. Because there is little or no interlayer gap between the multiple layers of tab sheets 320 within the compacted region 3211, pores caused by interlayer gaps are less likely to form in the molten pool of the compacted region 3211. By arranging at least a majority of the volume of the inner portion 412 within the compacted region 3211, this embodiment helps reduce pores formed in the inner portion 412, thereby improving the flow capacity of the connecting portion 4.

[0248] In some embodiments of the present application, the area ratio of the compacted region 3211 to the gathered portion 321 is greater than or equal to 40%. The area ratio can be understood as the ratio of the total area of ​​the compacted region 3211 on the outer surface of the gathered portion 321 to the area of ​​the outer surface of the gathered portion 321.

[0249] Therefore, by setting the area proportion of the compacted area 3211 to be greater than or equal to 40%, it is beneficial to increase the coverage of the compacted area 3211 on the gathered portion 321, which is beneficial to the design of the connecting portion 4, so that the connecting portion 4 can be distributed more in the compacted area 3211, improving the problem of thermal cracks in the contour of the connecting portion 4, improving the conductive yield and connection strength between the pole ear portion 32 and the conductive portion 20, improving the problem of air holes in the connecting portion 4, and improving the current flow capacity of the connecting portion 4, thereby improving the reliability of the battery cell 102.

[0250] For example, the compacted area 3211 accounts for 60% or more of the area of ​​the gathered portion 321. This allows the majority of the gathered portion 321 to be the compacted area 3211, which facilitates the design of the connection portion 4. This allows the connection portion 4 to be more distributed within the compacted area 3211, thereby improving the risk of thermal cracks in the contour of the connection portion 4, enhancing the conductivity yield and connection strength between the tab portion 32 and the conductive portion 20, and reducing the risk of pores within the connection portion 4. This improves the current carrying capacity of the connection portion 4, thereby enhancing the reliability of the battery cell 102.

[0251] In some embodiments of the present application, the compaction rate of the compacted region 3211 is greater than or equal to 6%. Therefore, by setting the compaction rate of the compacted region 3211 to be greater than or equal to 6%, the interlayer gaps in the compacted region 3211 can be reduced, and the portion of the connecting portion 4 falling within the compacted region 3211 is less likely to develop thermal cracks and pores, thereby improving the overall current carrying capacity of the connecting portion 4, as well as the reliability and conductivity yield of the connecting portion 4 connecting the conductive portion 20 and the gathered portion 321.

[0252] Exemplarily, the compaction rate of the compacted area 3211 is greater than or equal to 12%, thereby further reducing the gap in the compacted area 3211, making it possible to have almost no gap in the compacted area 3211, and the portion of the connecting part 4 that falls into the compacted area 3211 is less likely to have thermal cracks and air holes, thereby improving the overall current flow capacity of the connecting part 4, as well as the reliability and conductivity yield of the connecting part 4 connecting the conductive part 20 and the gathered part 321.

[0253] The following seven groups of experiments were conducted for comparison. In each experimental sample, 50 layers of tab sheets were stacked in the tab portion, the thickness of a single tab sheet was 13 μm, and the theoretical thickness T2 of the tab portion was 650 μm.

[0254] In Experiment 1, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 1 were obtained. Figure 22 shows the local cross-sectional morphology of the gathered part of Comparative Example 1. It can be seen that the thickness T1 of the compacted area is 765 μm, and the calculated compaction rate is -17.7%. Figure 23 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 100%.

[0255] In Experiment 2, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 2 were obtained. Figure 24 shows the local cross-sectional morphology of the gathered part of Comparative Example 2. It can be seen that the thickness T1 of the compacted area is 711 μm, and the calculated compaction rate is -9.4%. Figure 25 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 70%.

[0256] In Experiment 3, the ultrasonic pre-welding effect and laser welding effect of Comparative Example 3 were obtained. Figure 26 shows the local cross-sectional morphology of the gathered part of Comparative Example 3. It can be seen that the thickness T1 of the compacted area is 664 μm, and the calculated compaction rate is -2.2%. Figure 27 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 40%.

[0257] In Experiment 4, the ultrasonic pre-welding effect and laser welding effect of Example 1 were obtained. Figure 28 shows the local cross-sectional morphology of the gathered part of Example 1. It can be seen that the thickness T1 of the compacted area is 609 μm, and the calculated compaction rate is 6.3%. Figure 29 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that a small amount of thermal cracks appear in the outline of the laser weld, and the proportion of thermal cracks is close to 15%.

[0258] In Experiment 5, the ultrasonic pre-welding effect and laser welding effect of Example 2 were obtained. Figure 30 shows the local cross-sectional morphology of the gathered part of Example 2. It can be seen that the thickness T1 of the compacted area is 564 μm, and the calculated compaction rate is 13.2%. Figure 31 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that there is almost no thermal crack in the outline of the laser weld.

[0259] In Experiment 6, the ultrasonic pre-welding effect and laser welding effect of Example 3 were obtained. Figure 32 shows the local cross-sectional morphology of the gathered part of Example 3. It can be seen that the thickness T1 of the compacted area is 522 μm, and the calculated compaction rate is 19.7%. Figure 33 shows the local cross-sectional morphology of the gathered part and the conductive part after laser welding. It can be seen from the figure that there is no thermal crack in the outline of the laser weld.

[0260] In experiment seven, the ultrasonic pre-welding effect and laser welding effect of embodiment four were obtained. FIG34 shows the local cross-sectional morphology of the gathered portion of embodiment four. It can be seen that the thickness T1 of the compacted area is 362 μm, and the calculated compaction rate is 44.3%. FIG35 shows the local cross-sectional morphology of the gathered portion and the conductive portion after laser welding. It can be seen from the figure that there is no thermal crack in the outline of the laser weld.

[0261] Through the above experimental comparison, it can be found that when the compaction rate exceeds 6%, the problem of thermal cracks in the contour of the laser weld can be significantly improved. When the compaction rate exceeds 12%, the contour of the laser weld can basically be free of thermal cracks.

[0262] This application also provides a battery 100, comprising a battery cell 102 according to any of the above-described solutions. Because the reliability of the battery cell 102 according to the embodiments of this application is improved, this helps improve the reliability of the battery 100. It is worth noting that the battery 100 according to the embodiments of this application may or may not include a housing 101.

[0263] Exemplarily, the battery 100 further includes a busbar component, and there are multiple battery cells 102, and at least two of them are electrically connected through the busbar component. In this way, multiple battery cells 102 can be connected in series and / or in parallel. For example, when multiple battery cells 102 are connected in series, the anode of one battery cell 102 is connected to the cathode of the next battery cell 102 through a busbar component, and at the same time, the cathode of the battery cell 102 is connected to the anode of the previous battery cell 102 through another busbar component. For example, the busbar component can be directly or indirectly electrically connected to the pole body 21 in the pole component 2 to achieve electrical connection between the battery cell 102 and the busbar component.

[0264] The present application also provides an electrical device comprising the battery 100 of any of the aforementioned solutions. The battery 100 is configured to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems employing the battery 100. The improved reliability of the battery 100 improves the operating performance of the electrical device.

[0265] In conjunction with Figures 36 and 37, an embodiment of the present application further provides an ultrasonic welding device 2000, comprising: a drive cylinder 600, a welding seat 500 and a welding head 400. The drive cylinder 600 is arranged on a side of the welding head 400 away from the welding seat 500, and is used to drive the welding head 400 to move toward the welding seat 500. In conjunction with Figures 8 and 9, the welding end 401 of the welding head 400 has welding teeth 5 and tooth grooves 6. The welding teeth 5 are separated by the tooth grooves 6 into a plurality of tooth portions 51 arranged at intervals. The ultrasonic welding device 2000 is used to process the gathered portion 321 in any of the above-mentioned schemes, and the welding teeth 5 are used to process the compacted area 3211.

[0266] The compacted area 3211 corresponding to a single tooth 51 in the ultrasonic weld mark can be a common geometric shape such as a circle, square, or triangle, or a combination of these shapes. The weld tooth 5 corresponds to the compacted area 3211 in the ultrasonic weld mark, and the tooth groove 6 corresponds to the fluffy area 3212 in the ultrasonic weld mark. The cross-sectional metallographic view of the ultrasonic weld mark shows that the tab 320 in the compacted area 3211 is compressed and deformed, with the foil becoming thinner and turning grayish white. The tab 320 in the fluffy area 3212 is bright silver.

[0267] For example, referring to Figures 36 and 37 , the drive cylinder 600 is located directly above the ultrasonic welding device 2000. Below the drive cylinder 600, it is connected to the welding head 400 via guide rails, a conversion block, and the like. The drive cylinder 600, welding head 400, and welding base 500 are arranged sequentially from top to bottom in a straight line, making the ultrasonic welding process more stable, reducing mechanical losses, and causing negligible deformation of the welding head 400. During welding, the multi-layered tab 320 to be welded can be placed between the welding head 400 and the welding base 500. The drive cylinder 600 is activated, pushing the welding head 400 downward toward the welding base 500. The welding head 400 and welding base 500 weld the multi-layered tab 320 together, forming an ultrasonic weld mark. The drive cylinder 600 can be of any type, for example, an electric cylinder, a hydraulic cylinder, or a pneumatic cylinder. The welding base 500 can have any shape, for example, a conventional diagonal tooth pattern.

[0268] In the embodiment of the present application, the thickness T1 of the compacted region 3211 is less than the theoretical thickness T2 of the tab portion 32, resulting in a compaction rate greater than 0%, indicating that the tab 320 in the compacted region 3211 needs to be compressed and yielded and undergo plastic deformation. Therefore, according to the ultrasonic welding device 2000 of the embodiment of the present application, the surface pressure provided by the welding head 400 must be greater than the yield strength of the tab 320, such as the aluminum foil.

[0269] For example, under ultrasonic conditions, the yield strength of the tab 320, such as aluminum foil, is Rp 0.2 = σ, the length of the welding end 401 of the welding head 400 is J1, the width of the welding end 401 is J2, and the area of ​​the welding end 401 of the welding head 400 is S = J1 × J2. When the driving cylinder 600 is a cylinder, the pressure provided by the cylinder is P, the diameter of the cylinder is d, and the surface pressure provided by the welding head 400 is Pπ(d / 2) 2 / S, where Pπ(d / 2) 2 When / S≥σ, the tab 320 may be compressed and yielded and undergo plastic deformation, so that the compaction rate of the compacted area 3211 may be greater than 0%.

[0270] Therefore, on the one hand, the surface pressure of the welding head 400 can be increased by increasing the pressure P provided by the cylinder, increasing the diameter of the cylinder d, and reducing the area S of the welding end 401 to make the pole tab 320 yield and compact. On the other hand, the welding energy during ultrasonic welding can be increased. The cavitation effect of the ultrasound and the heat generated by the vibration friction of the pole tab 320 will reduce the yield strength of the pole tab 320, thereby improving the compaction rate of the compaction area 3211.

[0271] For example, when the driving cylinder 600 is a pneumatic cylinder, after the welding head 400 is selected, the area S of the welding end 401 is fixed, and the air supply pressure of the cylinder in the ultrasonic welding device 2000 can be adjusted to the maximum, such as the upper limit of the air supply pressure in the factory is usually 0.6 MPa. Afterwards, after welding with a cylinder with a diameter of usually 100 mm or 125 mm, the surface pressure provided by the welding head 400 is still less than the yield strength of the tab 320, such as aluminum foil. By increasing the diameter of the cylinder so that the diameter of the cylinder is greater than 125 mm, the surface pressure provided by the welding head 400 can be increased.

[0272] As mentioned above, if the tab 320 needs to be compressed and yielded and undergo plastic deformation, the surface pressure provided by the welding head 400 of the ultrasonic welding device 2000 must be greater than the yield strength of the tab 320, such as the aluminum foil. According to the above formula Pπ(d / 2) 2 / S≥σ, it can be seen that when the diameter of the cylinder needs to be increased, it can be calculated according to the formula d≥√4σS / Pπ.

[0273] For example, the ultrasonic weld mark size needs to meet 11mm×22mm, the ultrasonic welding device 2000 has an amplitude A=25μm, the cylinder pressure is P=0.41MPa, and the ultrasonic welding energy E=500J. The compaction rate is improved by increasing the welding time. The tab 320 is a 1-series aluminum alloy after roller pressing, with a yield strength of Rp0.2=75MPa. Under these ultrasonic conditions, the yield strength of the aluminum foil is reduced to Rp0.2 (ultrasonic effect)=35MPa. According to the formula, d≥√[(4×35×11×22) / (0.41×π)], that is, d≥162mm, which can make the aluminum tab yield and compact, so that the compaction rate of the compacted area 3211 can be greater than 0%.

[0274] For example, the cylinder has a diameter of 200 mm. This makes the cylinder relatively easy to machine and work, and it also has a high compaction rate, effectively improving the problem of thermal cracks in the laser weld profile, improving the conductivity yield and connection strength between the tab 32 and the conductive portion 20, and reducing porosity in the laser weld molten pool, thereby improving the laser weld's current capacity and enhancing the reliability of the battery cell 102.

[0275] For example, when the driving cylinder 600 is an electric cylinder, after the welding head 400 is selected, the area S of the welding end 401 is fixed, and the pressure that the electric cylinder can provide is F. When F / S≥σ, the tab 320 can be compressed to yield and undergo plastic deformation, so that the compaction rate of the compaction area 3211 can be greater than 0%.

[0276] In some embodiments of the present application, the tooth area ratio of the welding end 401 is greater than or equal to 40%. It is worth noting that the "tooth area ratio of the welding end 401" refers to the ratio of the area of ​​the welding tooth 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 tooth groove area on the welding end to the toothless area of ​​the welding end 401.

[0277] When the tooth area ratio of the welding end 401 is greater than or equal to 40%, after ultrasonic pre-welding, the area ratio of the compacted area 3211 relative to the gathered portion 321 can be greater than or equal to 40%. Therefore, by setting the tooth area ratio of the welding end 401 to be no less than 40%, the area ratio of the compacted area 3211 in the ultrasonic weld mark can be increased, so that the area ratio of the compacted area 3211 relative to the gathered portion 321 is greater than or equal to 40%, so that the contour line of the laser weld falls more into the compacted area 3211, so as to improve the problem of thermal cracks in the contour of the laser weld to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0278] Exemplarily, the tooth area of ​​the welding end 401 accounts for greater than or equal to 60%, thereby further increasing the area ratio of the compacted area 3211 in the ultrasonic weld mark, so that the area ratio of the compacted area 3211 relative to the gathered portion 321 is greater than or equal to 60%, so that the contour line of the laser weld falls more into the compacted area 3211, so as to improve the problem of thermal cracks in the contour of the laser weld to a greater extent, thereby improving the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and improving the reliability of the battery cell 102.

[0279] For example, by adjusting the welding teeth 5, the area of ​​the compacted area 3211 relative to the area of ​​the gathered portion 321 is 60% to 100%, which can provide a relatively sufficient compacted area 3211 for laser welding. Furthermore, 60% to 100% of the contour of the laser weld can be set in the compacted area 3211. For example, when viewed from the outer surface of the gathered portion 321, 60% to 100% of the contour of the laser weld falls within the solid area 3211. When viewed from the cross-section of the gathered portion 321, that is, from the interior of the gathered portion 321, 60% to 100% of the contour of the laser weld also falls within the solid area 3211. This can effectively improve the problem of thermal cracks in the contour of the laser weld, improve the conductivity yield and connection strength between the tab portion 32 and the conductive portion 20, and enhance the reliability of the battery cell 102.

[0280] In an embodiment of the present application, by improving the distribution, shape, size, etc. of the compacted area 3211 in the gathered portion 321 and correspondingly matching the shape, size and distribution position of the connecting portion 4, at least most of the contour lines of the connecting portion 4 formed by the connection between the conductive portion 20 and the pole ear portion 32 falling on the upper part of the gathered portion 321 fall on the compacted area 3211 of the gathered portion 321. In this way, the characteristic that the multi-layer pole ear sheets 320 are very tightly combined together in the compacted area 3211 can be utilized to improve the problem of thermal cracks in the contour of the connecting portion 4, improve the conductivity yield and connection strength between the pole ear portion 32 and the conductive portion 20, and enhance the current carrying capacity and reliability of the battery cell 102.

[0281] A specific embodiment of the present application is described below.

[0282] 38 , the welding end 401 of the welding head 400 divides the welding teeth 5 into two first tooth portions 514 , a plurality of second tooth portions 515 , and a plurality of third tooth portions 516 through the tooth grooves 6 . The profile of the first tooth portion 514 matches the profile of the second tooth portion 515 , and the profile of the first tooth portion 514 matches the profile of the third tooth portion 516 . The welding end 401 is in the shape of an elongated strip. The length direction of the first tooth portion 514 matches the length direction of the welding end 401. The width direction of the first tooth portion 514 matches the width direction of the welding end 401. The two first tooth portions 514 are spaced apart along the width direction of the welding end 401. Each long side of the first tooth portion 514 has a plurality of protrusions 5141 spaced apart along the length direction of the welding end 401. The protrusions 5141 protrude toward the width direction of the welding end 401. The plurality of second tooth portions 515 are disposed between the two first tooth portions 514, and the plurality of second tooth portions 515 are spaced apart along the length direction of the welding end 401. The protrusions 5141 on one side of the two first tooth portions 514 are positioned relative to each other, so that two opposing protrusions 5141 are respectively disposed between each adjacent two second tooth portions 515. The plurality of third tooth portions 516 are spaced apart and disposed around the two first tooth portions 514.

[0283] The ratio of the tooth tip length S7 of the first 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 first tooth portion 514 in the width direction of the welding end 401 to half the width J2 of the welding end 401 is 75%-85%, and the tooth area accounts for 70%-80%. Referring to Figure 39 , the groove width W0 of each tooth groove 6 is 0.2mm-0.4mm, the tooth height H4 of the first tooth portion 514 is 0.25mm, the projected distance E4 between the tooth tip and tooth bottom of the first tooth portion 514 is 0.1mm-0.2mm, and the edge of the welding end 401 is rounded with a rounding radius R4 of 1.5mm. The tooth area accounts for 70%-80% of the welding end 401. The length J1 of the welding end 401 is 25mm, and the width J2 is 14mm.

[0284] In conjunction with Figure 38, the third tooth portion 516 includes a first sub-tooth 5161 located on both sides of the two first tooth portions 514 in the width direction of the welding end 401, and a second sub-tooth 5162 located on both sides of the two first tooth portions 514 in the length direction of the welding end 401. There are multiple first sub-teeth 5161 and they are spaced apart along the length direction of the welding end 401. There are multiple second sub-teeth 5162 and they are spaced apart along the width direction of the welding end 401. The tooth top width S9 of the first sub-tooth 5161 in the length direction of the welding end 401 is 1.8mm-2.2mm, and the tooth top width S10 of the second sub-tooth 5162 in the width direction of the welding end 401 is 0.8mm-1.2mm.

[0285] The weld mark produced by the welding head of this embodiment is shown in Figures 13 and 40. The compacted region 3211 includes a first sub-region Z1 corresponding to the first tooth portion 514, a second sub-region Z2 corresponding to the second tooth portion 515, and a third sub-region Z3 corresponding to the third tooth portion 516. The first sub-region Z1 is elongated and matches the length and width of the gathered portion 321. There are two first sub-regions Z1, spaced apart along the width of the gathered portion 321. Each long side of the first sub-region Z1 has multiple protruding segments Z11 spaced apart along the length of the gathered portion 321. The protruding segments Z11 protrude toward the width of the gathered portion 321. Multiple second sub-regions Z2 are located between the two first sub-regions Z1 and spaced apart along the length of the gathered portion 321. The protruding segments Z11 of the adjacent two first sub-regions Z1 are positioned opposite each other, and two opposing protruding segments Z11 are provided between each pair of adjacent second sub-regions Z2. A plurality of third sub-regions Z3 are arranged around the two first sub-regions Z1 at intervals.

[0286] The ultrasonic weld mark produced by the welding head of this embodiment is laser welded to the conductive portion. The surface of the laser weld is shown in Figures 12 and 41. The two long sides 4x1 of the surface portion 411 correspond to the two first sub-zones Z1. The laser weld comprises a main weld and a base weld. Both the main weld and the base weld are welded using a spiral oscillating process. The two long sides of the main weld fall within the base weld, and the outer long sides of the base weld form the two long sides 4x1 of the surface portion 411. The interior of the laser weld is shown in Figures 11 and 42-44. The majority of the contour of the interior portion 412 falls within the compacted area 3211, and the laser weld profile is free of thermal cracks.

[0287] In this embodiment, a large-diameter cylinder is used in conjunction with a welding head having two large long strip teeth, which can effectively increase the area ratio of the compacted area 3211 relative to the welding end 401, and multiple small teeth are provided between and around the two large long strip teeth to provide welding grip, so that the foil can be firmly grasped during welding, which can provide greater friction.

[0288] Next, another specific embodiment of the present application is described.

[0289] Combined with Figure 45, 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 in the tooth groove 6. The welding end 401 is long and strip-shaped, and the first straight groove 61 is multiple and arranged in parallel. 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 is located in the center of the width of the welding end 401. The second straight groove 62 is cross-arranged with the multiple first straight grooves 61 to define a plurality of long strip-shaped fourth tooth portions 513. The welding end 401 as a whole presents a double-row long strip grid shape.

[0290] The tooth tip dimension S5 of the fourth tooth portion 513 in the spacing direction of the first linear groove 61 is 2 mm to 2.4 mm, and the tooth tip dimension S6 of the fourth tooth portion 513 in the length direction of the first linear groove 61 is 3.5 mm to 4.5 mm. The groove width W1 of the first linear groove 61 is 0.2 mm to 0.4 mm, and the groove width W2 of the second linear groove 62 is 0.4 mm to 0.6 mm. The tooth height of the fourth tooth portion 513 is 0.2 mm, and the projected distance between the tooth tip and tooth bottom of the fourth tooth portion 513 is 0.1 mm to 0.2 mm. The edge of the welding end 401 is rounded with a rounded radius of 1.5 mm. The tooth area of ​​the welding end 401 accounts for 60% to 70%. The length J1 of the welding end 401 is 25 mm, and the width J2 is 12 mm.

[0291] The weld mark produced by the welding head of this embodiment is shown in Figures 14 and 46. The compacted region 3211 includes a fourth sub-region Z5 corresponding to the fourth tooth portion 513. Multiple fourth sub-regions Z5 are arranged in a row along the length of the ultrasonic weld mark, with two rows of fourth sub-regions Z5 arranged on the ultrasonic weld mark. The ultrasonic weld mark produced by the welding head of this embodiment is laser welded to the conductive portion. The surface of the laser weld is shown in Figures 14 and 47. The two long sides 4x1 pass through the two rows of fourth sub-regions Z5, respectively. The laser weld includes a main weld and a root weld. Both the main weld and the root weld are welded using a spiral oscillating process. The two long sides of the main weld fall within the root weld, and the outer long sides of the root weld form the two long sides 4x1 of the surface portion 411. The interior of the laser weld is shown in Figures 11 and 48. The majority of the contour of the interior portion 412 falls within the compacted region 3211, and the laser weld profile is free of thermal cracks.

[0292] Next, another specific embodiment of the present application is described.

[0293] Combined with Figure 49, the welding end 401 of the welding head 400 is divided into welding teeth 5 by a first straight groove 61 and a second straight groove 62. The welding end 401 is in the shape of a long strip. The first straight groove 61 is multiple and 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 is located in the center of the width of the welding end 401. The second straight groove 62 is cross-arranged with the multiple first straight grooves 61 to define multiple fifth tooth portions 517. The welding end 401 as a whole presents a double-row checkered shape.

[0294] The tooth tip dimension S11 of the fifth tooth portion 517 in the spacing direction of the first linear slot 61 is 4.5 mm to 5.5 mm, and the tooth tip dimension S12 of the fifth tooth portion 517 in the length direction of the first linear slot 61 is 5 mm to 6 mm. The groove width W1 of the first linear slot 61 is 0.3 mm to 0.9 mm, and the groove width W2 of the second linear slot 62 is 0.3 mm to 0.9 mm. The tooth area of ​​the welding end 401 accounts for 70% to 90%. The length J1 of the welding end 401 is 22 mm, and the width J2 is 12 mm.

[0295] The weld mark produced by the welding head of this embodiment is shown in Figures 50 and 51. The compacted region 3211 includes a fifth sub-region Z6 corresponding to the fifth tooth portion 517. Multiple fifth sub-regions Z6 are arranged in a row along the length of the ultrasonic weld mark, with two rows of fifth sub-regions Z6 arranged on the ultrasonic weld mark. The ultrasonic weld mark produced by the welding head of this embodiment is laser welded to the conductive portion. In conjunction with Figure 15, each fifth sub-region Z6 has a laser weld. Figures 52-55 show schematic diagrams of the laser weld at one of the fifth sub-regions. The laser weld includes a main weld and a root weld. The root weld is annular and the main weld is circular. The laser weld profile is free of thermal cracks. The root weld is welded first, and the entire root weld falls within the compacted region. The penetration of the root weld is exactly equal to the thickness of the compacted region. After the root weld is completed, the main weld is welded, and the outer contour of the main weld pool falls within the molten pool of the root weld.

[0296] In addition, the embodiments of this application are also applicable to batteries for 3C products, such as small batteries used in mobile phones and other devices. Batteries for 3C products have fewer tab layers and narrower tab widths. A flat welding head with spark erosion can be used for roughening, or a welding head with low weld teeth (e.g., tooth height ≤ 0.1mm) can be used. For example, power batteries typically have 30-120 tab layers, with a thickness of 13μm-15μm and a tooth height of 0.1mm-0.4mm. Batteries for 3C products typically have 10-50 tab layers, with a thickness of 6μm-10μm. The width of the ultrasonic weld mark is approximately 5mm, and the tooth height can be less than 0.1mm. Laser welding can use a high-frequency pulsed laser or a low-power continuous laser, and 60% to 100% of the laser weld contour should fall within the compacted area to improve battery reliability.

[0297] During the production of battery cells, ultrasonic welding can be used to pre-weld multiple tabs in the tab portion to form an ultrasonic weld mark, and then laser welding can be used to weld the ultrasonic weld mark to the conductive portion of the pole column component to achieve connection and electrical conduction between the electrode assembly and the pole column component. However, in the ultrasonic welding machine used for ultrasonic welding in the related art, after pre-welding the tab portion, the ultrasonic weld mark cannot form an effective interlayer weld. There are interlayer gaps between the multiple layers of tab sheets. The presence of these gaps will increase the porosity in the molten pool of the laser weld, reducing the flow capacity of the battery cell. In addition, during the cooling stage after laser welding, the contour of the laser weld will form thermal cracks, which will affect the connection reliability and conductivity yield between the tab portion and the conductive portion, and thus affect the performance of the battery cell.

[0298] The ultrasonic welding device provided in the embodiment of the present application can increase the cylinder diameter, increase the welding pressure, increase the compaction rate after ultrasonic pre-welding, reduce the gap between the tab layers, and then match the welding tooth design of the welding head to increase the area of ​​the compaction area and optimize the distribution of the compaction area, thereby helping to improve the problem of thermal crack deterioration caused by the contour of the laser weld, and reduce the proportion of pores in the laser weld molten pool, thereby improving the connection reliability and conductivity yield between the tab part and the conductive part, and improving the current flow capacity of the battery cell and improving the performance of the battery cell.

[0299] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0300] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, wherein: include: Shell components; A pole component is provided on the housing component, and the pole component includes a conductive portion; an electrode assembly housed in the housing component and comprising a tab portion, the tab portion comprising a plurality of tab sheets stacked together, the plurality of tab sheets being connected to form a gathered portion, the gathered portion being stacked and connected to the conductive portion to form a connecting portion; The gathered portion includes a compacted area, the thickness of which is less than the stacking thickness of the multiple pole tab sheets in the pole tab portion, and the connecting portion includes a first part formed in the gathered portion, at least most of the contour line of the first part is located in the compacted area.

2. The battery cell according to claim 1, wherein: The connecting portion extends from an outer surface of the gathered portion toward the conductive portion, and the first portion includes a surface portion formed on the outer surface of the gathered portion.

3. The battery cell according to claim 2, wherein: At least a majority of the area of ​​the surface portion falls within the compacted region.

4. The battery cell according to claim 2 or 3, wherein: At least a substantial portion of the contour of the surface portion lies within the compacted region.

5. The battery cell according to claim 4, wherein: More than 60% of the contour of the surface portion lies within the compacted area.

6. The battery cell according to any one of claims 2 to 5, wherein: The surface of the gathered portion is in the shape of an elongated strip, the surface portion is in the shape of an elongated strip and matches the length direction of the gathered portion, and at least a majority of each of the two long sides of the surface portion is located in the compacted area.

7. The battery cell according to claim 6, wherein: The compacted area includes a first sub-area, which is long and narrow and matches the length and width directions of the gathered portion respectively. The length of the first sub-area exceeds half of the length of the gathered portion. There are two first sub-areas and they are spaced apart along the width direction of the gathered portion. The two long sides of the surface portion are respectively located in the two first sub-areas.

8. The battery cell according to claim 7, wherein: Each long side of the first sub-region has a plurality of protruding sections arranged at intervals along the length direction of the gathering portion, and the protruding sections protrude toward the width direction of the gathering portion.

9. The battery cell according to claim 8, wherein: The compacted area includes a plurality of second sub-areas arranged between two of the first sub-areas and spaced apart along the length direction of the gathered portion. The protruding segments on one side of the two first sub-areas are positioned opposite to each other, and two opposing protruding segments are respectively arranged between each two adjacent second sub-areas.

10. The battery cell according to claim 9, wherein: The gathering portion includes a fluffy area, and the fluffy area includes a first fluffy area arranged between the two first sub-areas and separated between the two first sub-areas and between the first sub-area and the second sub-area. The first fluffy area is in the form of a line on the outer surface of the gathering portion so that the outline of the second sub-area matches the outline of the first sub-area.

11. The battery cell according to any one of claims 7 to 9, wherein: The compacting region includes a plurality of third sub-regions, and the third sub-regions are arranged in a plurality and spaced apart from each other around the two first sub-regions.

12. The battery cell according to claim 11, wherein: The gathering portion includes a fluffy area, and the fluffy area includes a second fluffy area arranged at the outer periphery of the two first sub-areas, and separated between the first sub-area and the third sub-area and between two adjacent third sub-areas. The second fluffy area is in the form of a line on the outer surface of the gathering portion so that the outline of the third sub-area matches the outline of the first sub-area.

13. The battery cell according to claim 6, wherein: The compaction area includes a plurality of first compaction rows spaced apart along the width direction of the gathering portion, each of the first compaction rows includes a plurality of fourth sub-areas spaced apart along the length direction of the gathering portion, the two long sides of the surface portion are respectively arranged corresponding to two of the first compaction rows, and each long side passes through a plurality of the fourth sub-areas in the corresponding first compaction row, and the size of the fourth sub-area in the length direction of the gathering portion is greater than the spacing between two adjacent fourth sub-areas in the length direction of the gathering portion.

14. The battery cell according to claim 13, wherein: There are two first compaction rows, the fourth sub-region is long and narrow, and the length direction of the fourth sub-region matches the width direction of the gathering portion, the width direction of the fourth sub-region matches the length direction of the gathering portion, and the length of the fourth sub-region exceeds one quarter of the width of the gathering portion.

15. The battery cell according to claim 13 or 14, wherein: The gathering portion includes a fluffy area, and the fluffy area includes a third fluffy area separated between two adjacent fourth sub-areas in the same first compaction row, and a fourth fluffy area separated between two adjacent first compaction rows. The third fluffy area is in the form of a line extending along the width direction of the gathering portion on the outer surface of the gathering portion, and the fourth fluffy area is in the form of a line extending along the length direction of the gathering portion on the outer surface of the gathering portion. The width of the third fluffy area is smaller than the width of the fourth fluffy area.

16. The battery cell according to any one of claims 2 to 5, wherein: The surface portion is entirely located in the compacted area.

17. The battery cell according to claim 16, wherein: The compacted area includes a plurality of fifth sub-areas that are spaced apart, and the surface portion is spaced apart and arranged in a one-to-one correspondence with the plurality of fifth sub-areas.

18. The battery cell according to claim 17, wherein: The compacting region includes a plurality of second compacting rows spaced apart along a width direction of the gathered portion, and each of the second compacting rows includes a plurality of fifth sub-regions spaced apart along a length direction of the gathered portion.

19. The battery cell according to claim 18, wherein: There are two second compacted rows, and the dimensions of the fifth sub-area in the width direction of the gathered portion and in the length direction of the gathered portion both exceed a quarter of the width of the gathered portion.

20. The battery cell according to any one of claims 2 to 19, wherein: The connecting portion includes a first connecting portion and a second connecting portion, the second connecting portion extends into the conductive portion, the extension depth of the first connecting portion is smaller than the extension depth of the second connecting portion, the surface portion includes a first surface portion of the first connecting portion formed on the outer surface of the gathered portion, and a second surface portion of the second connecting portion formed on the outer surface of the gathered portion, at least most of the contour line of the second surface portion is located within the first surface portion.

21. The battery cell according to claim 20, wherein: The shape of the first face portion matches the shape of the contour line of the second face portion, and at least a majority of the contour line of the second face portion falls in a central position of the first face portion.

22. The battery cell according to claim 20 or 21, wherein: The surface of the gathering portion is long and strip-shaped, the surface portion is long and strip-shaped and matches the length direction of the gathering portion, the first face portion is long and strip-shaped extending along the length direction of the gathering portion and is arranged at intervals along the width direction of the gathering portion, and the second face portion is long and strip-shaped extending along the length direction of the gathering portion, and the two long sides of the second face portion fall within the two first face portions respectively.

23. The battery cell according to claim 20 or 21, wherein: There are multiple surface parts that are spaced apart. Each surface part includes the first face portion and the second face portion. The first face portion is annular and surrounds the corresponding second face portion. The outline of the second face portion is located within the corresponding first face portion.

24. The battery cell according to any one of claims 20 to 23, wherein: The extending depth of the first connecting portion is 60%-100% of the thickness of the compacted area.

25. The battery cell according to any one of claims 20 to 24, wherein: The connecting portion also includes a third connecting portion, the extension depth of the third connecting portion is smaller than the extension depth of the first connecting portion, the third connecting portion is arranged on a side of the first connecting portion away from the second connecting portion, and the surface portion also includes a third surface portion formed by the third connecting portion on the outer surface of the gathered portion, and at least part of the contour line of the first surface portion is located within the third surface portion.

26. The battery cell according to claim 25, wherein: At least a majority of the outline of the first face portion is located within the third face portion.

27. The battery cell according to claim 26, wherein: The shape of the third face portion matches the outline shape of the first face portion, and at least a majority of the outline of the first face portion falls in a central position of the third face portion.

28. The battery cell according to any one of claims 25 to 27, wherein: The extending depth of the third connecting portion is 20%-60% of the thickness of the compacted area.

29. The battery cell according to any one of claims 1 to 28, wherein: The first portion includes an inner portion formed within the gathered portion, and at least a majority of a contour of the inner portion falls within the compacted region.

30. The battery cell according to claim 29, wherein More than 60% of the contour of the inner portion falls within the compacted area.

31. The battery cell according to claim 29 or 30, wherein: At least a majority of the volume of the interior portion falls within the compacted region.

32. The battery cell according to any one of claims 1 to 31, wherein: The compacted area accounts for more than or equal to 40% of the area of ​​the gathered portion.

33. The battery cell according to claim 32, wherein: The compacted area accounts for more than or equal to 60% of the area of ​​the gathered portion.

34. The battery cell according to any one of claims 1 to 33, wherein: The compaction rate of the compacted area is greater than or equal to 6%.

35. The battery cell according to claim 34, wherein The compaction rate of the compacted area is greater than or equal to 12%.

36. A battery, wherein: The invention comprises a battery cell according to any one of claims 1 to 35.

37. An electrical device, wherein: Comprising a battery according to claim 36.

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