Welding method and battery

Abstract

The application provides a welding method and a battery, which comprises the following steps: ultrasonic pre-welding the tab on the core package according to a first welding area to form an ultrasonic pre-welding tab, wherein the first welding area is determined according to the size and shape of the pole; laser welding the ultrasonic pre-welding tab and the pole according to a second welding area to complete the connection of the tab and the pole, wherein the ratio of the second welding area to the first welding area is less than 1, which can ensure that the tab is completely attached to the pole, ensure the overcurrent capacity of the tab under the premise of realizing the stability of welding, ensure the rationality and maximization of the second welding area, effectively improve the overcurrent capacity of the connection between the tab and the pole, and reduce the temperature rise; meanwhile, the laser welding mode forms a complete path between the tab and the pole, and greatly improves the battery yield.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a welding method and a battery. Background Technology

[0002] In the battery manufacturing process, the tabs on the battery cell pack need to be connected to the cover plate so that the terminals on the cover plate can communicate with the cell pack. The connection between the cell pack and the cover plate is usually done by welding, and the welding parameters have a great impact on the battery yield.

[0003] In related technologies, when batteries undergo welding processes during assembly, the weld area, weld shape, and welding parameters are all set by relevant process personnel based on past experience. The rationality and scientific validity of these parameter settings cannot be guaranteed, which can lead to welding defects such as missed welds and incomplete welds during battery manufacturing, thus affecting the battery yield. Summary of the Invention

[0004] The embodiments of the present invention provide a welding method and a battery, which can improve the technical problem of poor welding caused by manually determining the welding parameters of the tab and the post, thus reducing the battery yield.

[0005] In a first aspect, embodiments of the present invention provide a welding method, the method comprising:

[0006] The tabs on the core package are ultrasonically pre-welded according to the first solder mark area to form ultrasonically pre-welded tabs, wherein the first solder mark area is determined according to the size and shape of the pole post;

[0007] Laser welding is performed on the ultrasonic pre-welded tab and the electrode post according to the second weld area to complete the connection between the tab and the electrode post, wherein the ratio of the second weld area to the first weld area is less than 1.

[0008] In one embodiment, the pole post is square, circular, or elliptical in shape, and the corresponding dimensions of the pole post are length a, width b, radius r, minor axis c, and major axis d.

[0009] In one embodiment, the method includes: if the shape of the pole post is square, then the length a is adjusted according to a first preset adjustment coefficient λ1 to obtain an adjusted length, wherein 0 < λ1 < 1;

[0010] The width b is adjusted according to the second preset adjustment coefficient λ2 to obtain the adjusted width, where 0 < λ2 < 1;

[0011] The first solder area is determined based on the adjustment length and the adjustment width;

[0012] Preferably, 0.7 < λ1 < 0.9;

[0013] Preferably, 0.3 < λ2 < 0.5. In one embodiment, the method includes: if the shape of the pole is circular, adjusting the radius r according to a third preset adjustment coefficient λ3 to obtain an adjusted radius, wherein 0 < λ3 < 1;

[0014] The area of ​​the first solder mark is determined based on the adjustment radius;

[0015] Preferably, 0.75 < λ3 < 0.9. In one embodiment, the method includes: if the shape of the pole post is elliptical, adjusting the short semi-axis c according to a fourth preset adjustment coefficient λ4 to obtain an adjusted short semi-axis, where 0.85 < λ4 < 0.95;

[0016] The semi-axis d is adjusted according to the fifth preset adjustment coefficient λ5 to obtain the adjusted semi-axis, where 0 < λ5 < 1;

[0017] The first solder area is determined based on the adjusted short half-axis and the adjusted long half-axis;

[0018] Preferably, 0.85 < λ4 < 0.95;

[0019] Preferably, 0.85 < λ5 < 0.95.

[0020] In one embodiment, the ratio of the second solder area to the first solder area is μ, and 0.6 < μ < 0.8.

[0021] In one embodiment, before performing ultrasonic pre-soldering on the tabs on the core package according to the first solder area, the method further includes:

[0022] The closing size of the tab is determined based on the thickness of the core package;

[0023] The tabs are folded and pressed together according to the stated folding dimensions.

[0024] In one embodiment, it includes:

[0025] The thickness of the core pack is 1mm-700mm, and the folded-up size is 1mm-500mm;

[0026] Alternatively, the collapsible dimension is less than or equal to the thickness of the core package;

[0027] Preferably, the ratio of the gathered size to the thickness of the core package is 1 / 5 to 1;

[0028] Preferably, the ratio of the gathered size to the thickness of the core package is 1 / 4 to 5 / 7.

[0029] In one embodiment, the step of laser welding the ultrasonic pre-welded tab to the electrode post according to the second solder area includes:

[0030] Obtain the preset welding shape for laser welding;

[0031] The laser welding trajectory is determined based on the second weld area and the preset welding shape;

[0032] The ultrasonic pre-welded tab and the electrode post are laser welded according to the laser welding trajectory.

[0033] In one embodiment, the ratio of the area of ​​the first solder mark to the area of ​​the pole post is greater than or equal to 0.32 and less than or equal to 0.81;

[0034] And / or, the ratio between the perimeter of the trajectory corresponding to the laser welding and the perimeter of the trajectory corresponding to the ultrasonic pre-welding is less than 1.

[0035] In a second aspect, embodiments of the present invention provide a battery including a core pack and a cover plate, wherein the core pack includes tabs, the cover plate includes terminals, and the tabs and terminals are connected by a welding method as described in any one of the first aspects.

[0036] The beneficial effects of the embodiments of the present invention are as follows:

[0037] In embodiments of the present invention, the first solder area is determined based on the size and shape of the electrode post to ensure its rationality. Based on the first solder area, the tabs on the core pack are ultrasonically pre-welded according to the first solder area, reducing the interlayer gap between the tabs and making the tabs a tight whole, reducing abnormalities such as incomplete welding that may occur during laser welding. The ultrasonically pre-welded tabs and the electrode post are then laser-welded according to the second solder area. Since the second solder area is smaller than the first solder area, it can be ensured that the tabs are completely attached to the electrode post. Under the premise of achieving welding stability, the current carrying capacity of the tabs is guaranteed, ensuring the rationality and maximization of the second solder area, effectively improving the current carrying capacity at the connection between the tabs and the electrode post, and reducing the temperature rise. Moreover, the laser welding method forms a complete path between the tabs and the electrode post, greatly improving the battery yield. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic flowchart of one embodiment of the welding method provided by the present invention;

[0040] Figure 2 This is a schematic diagram showing the relationship between the folded size and the thickness of the core pack provided in the embodiments of this application;

[0041] Figure 3 This is a schematic diagram comparing the tensile strength of two laser-welded battery shapes provided in the embodiments of this application;

[0042] Figure 4 This is a schematic diagram comparing the test internal resistance of two types of laser-welded batteries provided in the embodiments of this application;

[0043] Figure 5 This is a schematic diagram comparing the discharge temperature rise of two laser-welded battery shapes provided in the embodiments of this application;

[0044] Figure 6 This is a schematic diagram of the welding connection between the tab and the terminal post in the battery provided in the embodiments of this application. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0046] like Figure 1 The diagram shown is a schematic flow chart of one embodiment of the welding method in this application. The welding method includes:

[0047] 101. Perform ultrasonic pre-welding on the tabs on the core package according to the first solder mark area to form ultrasonic pre-welded tabs, wherein the first solder mark area is determined according to the size and shape of the pole post.

[0048] This welding method is used to connect the cell pack and the cover plate in a battery. The battery includes a cell pack and a cover plate, and the cell pack has tabs, which are multi-layered tabs. The cover plate includes terminal posts. In this embodiment, the battery is constructed by connecting the cell pack and the cover plate.

[0049] The shape of the electrode refers to the shape of the electrode on the cover plate, such as square, round, or elliptical. The size of the electrode refers to the dimensions of the electrode on the cover plate under different shapes, such as radius, length, and width. The first solder area refers to the parameters of a solder trajectory in the ultrasonic pre-welding method for the electrode tab. Since the proper setting of the first solder area affects the battery's overcurrent capacity and temperature rise, in this embodiment, the first solder area is determined by detecting the size and shape of the electrode. The influence of the shape and related dimensions of the cover plate electrode on the ultrasonic solder area is considered to ensure the rationality of the first solder area, thereby ensuring the accuracy of subsequent welding and avoiding welding defects.

[0050] It is worth noting that, because the laser beam is sensitive to the gap between the layers of the welding material, as the number of tab layers increases, the gap between the bottom layers becomes larger, making it more difficult for the laser to penetrate and causing incomplete welds. The tighter the gap between the tab layers, the better the fusion of the substrate and the less likely it is to cause incomplete welds. Therefore, the use of ultrasonic pre-welding can reduce the gap between the tab layers, making the tabs a tight whole and reducing abnormalities such as incomplete welds that may occur during laser welding.

[0051] Furthermore, the shape of the pole post is one of square, circular or elliptical, and the corresponding dimensions of the pole post are length a, width b, radius r, minor axis c and major axis d.

[0052] Specifically, when the pole is square, its corresponding pole dimensions are length a and width b; when the pole is circular, its corresponding pole dimension is radius r; and when the pole is elliptical, its corresponding pole dimensions are minor axis c and major axis d.

[0053] Further, if the pole post is square, the length a is adjusted according to a first preset adjustment coefficient λ1 to obtain an adjusted length, where 0 < λ1 < 1; the width b is adjusted according to a second preset adjustment coefficient λ2 to obtain an adjusted width, where 0 < λ2 < 1; the first solder area is determined based on the adjusted length and the adjusted width; preferably, 0.7 < λ1 < 0.9; preferably 0.3 < λ2 < 0.5.

[0054] Specifically, when the electrode post is square, the length *a* and width *b* of the electrode post can be adjusted according to the corresponding first preset adjustment coefficient λ1 and second preset adjustment coefficient λ2, respectively, to obtain the adjusted length λ1*a and adjusted width λ2*b. Based on the adjusted length λ1*a and adjusted width λ2*b, the first solder area *S* can be calculated using the formula for calculating the area of ​​a square. 超声= (λ1*a)*(λ2*b), and since 0.7<λ1<0.9 and 0.3<λ2<0.5, the area of ​​the first solder mark is smaller than the area of ​​the pole post. Under the premise of ensuring reasonableness, the adjustment length and adjustment width are maximized, ensuring the rationality and maximization of the first solder mark area, reducing the welding redundancy of the tabs in the battery pack, and ensuring the safety of the pack.

[0055] In one specific implementation, λ1 = 0.8, λ2 = 0.4, then S 超声 = (0.8*a)*(0.4*b) = 0.32ab. Understandably, in this embodiment, by adjusting the length a and width b of the square pole, and for the square pole, the length a is adjusted to 0.8 times the original and the width b is adjusted to 0.4 times the original, compared with the traditional manual experience setting, the reasonable accuracy of the calculation of the first solder area is improved, which is conducive to improving the accuracy of ultrasonic pre-welding.

[0056] Furthermore, if the pole post is circular, the radius r is adjusted according to a third preset adjustment coefficient λ3 to obtain an adjustment radius, where 0 < λ3 < 1; the first solder area is determined based on the adjustment radius; preferably, 0.75 < λ3 < 0.9.

[0057] Specifically, when the electrode post is circular, the radius r of the electrode post can be adjusted according to the third preset adjustment coefficient λ3 to obtain the adjustment radius λ3*r. Based on the adjustment radius λ3*r, the first solder area S can be calculated using the formula for calculating the area of ​​a circle. 超声 =π*(λ3*r)*(λ3*r), and since 0.75<λ3<0.9, the area of ​​the first solder mark is smaller than the area of ​​the pole post. Under the premise of ensuring reasonableness, the adjustment radius is maximized, ensuring the rationality and maximization of the first solder mark area, reducing the welding redundancy of the tabs of the battery core pack, and ensuring the safety of the core pack.

[0058] In one specific implementation, λ3 = 0.8, then S 超声 =π*(0.8*r)*(0.8*r)=0.64*r 2 Understandably, in this embodiment, by adjusting the radius r of the circular pole, and for the circular pole, the radius r is adjusted to 0.8 times the original value, the reasonable accuracy of the calculation of the first solder area is improved compared with the traditional manual experience setting, which is conducive to improving the precision of ultrasonic pre-welding.

[0059] Further, if the pole post is elliptical in shape, the short semi-axis c is adjusted according to a fourth preset adjustment coefficient λ4 to obtain an adjusted short semi-axis, where 0 < λ4 < 1; the long semi-axis d is adjusted according to a fifth preset adjustment coefficient λ5 to obtain an adjusted long semi-axis, where 0 < λ5 < 1; the first solder area is determined based on the adjusted short semi-axis and the adjusted long semi-axis; preferably, 0.85 < λ4 < 0.95; preferably, 0.85 < λ5 < 0.95.

[0060] Specifically, when the electrode post is elliptical in shape, the minor axis c and major axis d of the electrode post can be adjusted according to the corresponding fourth preset adjustment coefficient λ4 and fifth preset adjustment coefficient λ5, respectively, to obtain the adjusted minor axis λ4*c and the adjusted major axis λ5*d. Based on the adjusted minor axis λ4*c and the adjusted major axis λ5*d, the first solder area S can be calculated according to the formula for calculating the area of ​​an ellipse. 超声 =*(λ4*c)*

[0061] (λ5*d), and since 0.85<λ4<0.95 and 0.85<λ5<0.95, the area of ​​the first solder mark is smaller than the area of ​​the pole post. Under the premise of ensuring reasonableness, the adjustment length and adjustment width are maximized, ensuring the rationality and maximization of the first solder mark area, reducing the welding redundancy of the tabs of the battery core pack, and ensuring the safety of the core pack.

[0062] In one specific implementation, λ4 = 0.9, λ5 = 0.9, then S 超声 =0.81*π*(λ4*c)*(λ5*d)=0.81*π*c*d. Understandably, in this embodiment, by adjusting the minor semi-axis c and major semi-axis d of the elliptical pole, and for the elliptical pole, adjusting the minor semi-axis c to 0.9 times the original value and the major semi-axis d to 0.9 times the original value, compared to traditional manual experience-based settings, the reasonable accuracy of the first solder area calculation is improved, which is beneficial to improving the precision of ultrasonic pre-welding.

[0063] 102. Laser welding is performed on the ultrasonic pre-welded tab and the electrode post according to the second solder area to complete the connection between the tab and the electrode post, wherein the ratio of the second solder area to the first solder area is less than 1.

[0064] The second weld area refers to the parameters of a weld trace when the ultrasonic pre-welded tab and the electrode post are laser-welded. Since ultrasonic pre-welding alone is not enough to guarantee the stability of the welding, there may be incomplete welding or poor weld marks. Therefore, in this embodiment, on the basis of ultrasonic pre-welding, laser welding is performed on the ultrasonic pre-welded tab and the electrode post to form a complete path between the tab and the electrode post to realize the charging and discharging of the current.

[0065] Specifically, the ratio of the second weld area to the first weld area is less than 1, that is, the second weld area is smaller than the first weld area. This takes into account the influence of the first weld area on the area of ​​laser welding, ensuring the rationality of the second weld area, thereby ensuring the accuracy of laser welding and avoiding welding defects.

[0066] Furthermore, the ratio of the second solder area to the first solder area is μ, and 0.6 < μ < 0.8.

[0067] Specifically, the sparser the connection between the tabs and the cover plate, the more energy transfer pathways there are inside the battery, thus improving energy transfer capability and effectively increasing current carrying capacity. Simultaneously, the increased pathways reduce energy concentration, effectively lowering battery temperature rise. Since a reasonable laser soldering area needs to be set, the battery's current carrying capacity and temperature rise are closely related to the second soldering area. A larger second soldering area results in better current carrying capacity and temperature rise, but also lower manufacturability. When the second soldering area is 0.6 to 0.8 times the ultrasonic pre-welding area, its manufacturability is high, and its current carrying capacity and temperature rise control are good. Therefore, in this embodiment, the second soldering area is adjusted to 0.6-0.8 times the first soldering area. As a preferred embodiment, the laser soldering area S... 激光 =0.8S 超声 This maximizes the area of ​​the second solder mark, improving its rationality and accuracy.

[0068] Further, the step of laser welding the ultrasonic pre-welded tab and the electrode post according to the second weld area includes: obtaining a preset welding shape for laser welding; determining a laser welding trajectory based on the second weld area and the preset welding shape; and laser welding the ultrasonic pre-welded tab and the electrode post according to the laser welding trajectory.

[0069] The preset welding shape for laser welding is a pre-defined shape used for laser welding. For example, the preset welding shape is a pentagram, triangle, polygon, or irregular shape.

[0070] Specifically, the preset welding shape is a pentagon, triangle, polygon or irregular shape. It is worth noting that the design of the second weld area is simpler and more convenient due to the regular shape. Therefore, as a preferred embodiment, the preset welding shape is a regular shape, such as an ellipse or square.

[0071] Specifically, a laser weld with a preset welding shape and an area equal to the second weld area is applied between the ultrasonically pre-welded tab and the terminal post, completing the laser weld between the ultrasonically pre-welded tab and the terminal post. More specifically, the size of the preset welding shape is calculated based on the second weld area and the preset welding shape, and the laser welding trajectory is calculated based on the size and the preset welding shape. The final laser weld is then performed between the ultrasonically pre-welded tab and the terminal post according to the laser welding trajectory, thus realizing the welding of the tab and the terminal post in the battery. Because the second weld area is reasonable and accurate, the battery yield is improved.

[0072] Furthermore, before performing ultrasonic pre-welding on the tabs on the core package according to the first solder area, the method further includes: determining the folding size of the tabs based on the thickness of the core package; and folding and pressing the tabs according to the folding size.

[0073] Among them, the closing dimension is the positioning dimension of the clamp when the tabs are closed.

[0074] Specifically, assembly can be performed after the tabs are slit and die-cut. Assembly methods include, but are not limited to, stacking or winding. Then, the thickness H of the core package is obtained based on the core package model or core package parameter information. 芯厚 The closing dimensions of the positive and negative tabs within the core package are determined based on the core package thickness to ensure sufficient density between the tabs during ultrasonic pre-welding of the assembled core package. Understandably, in this embodiment, determining the closing dimensions based on the core package thickness fully considers the impact of the core package thickness on the subsequent tab welding yield, avoiding edge damage to the solder joints caused by tab pulling.

[0075] Furthermore, the thickness of the core package is 1mm-700mm, and the folded-up size is 1mm-500mm;

[0076] Alternatively, the folded size is less than or equal to the thickness of the core package; preferably, the ratio of the folded size to the thickness of the core package is 1 / 5 to 1; preferably, the ratio of the folded size to the thickness of the core package is 1 / 4 to 5 / 7.

[0077] Specifically, the folding size H of the electrode tab 收拢 It can be the thickness H of the core package 芯厚 1 / 4 to 5 / 7 of the original size. Preferably, the gathered size H... 收拢 =H 芯厚 *1 / 4, and makes the first layer of tabs more spacious. After being gathered according to this formula, the tabs will not be pulled during subsequent laser welding, preventing damage to the weld edge and improving the tab yield. For example... Figure 2 As shown, the collapsed size H 收拢 With the thickness H of the core package 芯厚 A diagram showing the size relationship between the dimensions.

[0078] In one example, H 芯厚 The size range is 1mm-700mm, and the collapsed size H 收拢 The size range is 1mm-500mm. For example, H 芯厚 When the thickness is 1mm, the shrinkage dimension H 收拢 If the thickness is 1mm, then the first layer tab is not wide enough. When H 芯厚 When the diameter is 700mm, the collapsed dimension H 收拢 The diameter is 500mm, and the first layer of tabs is relatively spacious.

[0079] Further, the ratio of the area of ​​the first solder mark to the area of ​​the pole post is greater than or equal to 0.32 and less than or equal to 0.81; and / or, the ratio between the perimeter of the trajectory corresponding to the laser welding and the perimeter of the trajectory corresponding to the ultrasonic pre-welding is less than 1.

[0080] Specifically, the battery's overcurrent and temperature rise are closely related to the area of ​​the laser-welded terminal block. A larger laser-welded terminal block area results in better overcurrent capacity and temperature rise, but also lower processing and manufacturability. When the terminal block is square, and the laser-welded terminal block is also square, the area is maximized when the length of the square laser-welded terminal block is 0.8 times the length of the terminal block and the width is 0.4 times the width of the terminal block. This results in higher processing and manufacturability and better overcurrent capacity. When the force and temperature rise are well controlled, the ratio of the area of ​​the ultrasonic pre-welding to the area of ​​the electrode is 0.32. When the electrode is elliptical and the shape of the laser final weld is also elliptical, the laser final weld area is the largest when the major semi-axis of the laser final weld is 0.9 times the major semi-axis of the electrode and the minor semi-axis is 0.9 times the minor semi-axis of the electrode. The processing and manufacturability are high, and the current carrying capacity and temperature rise control are good. At this time, the ratio of the area of ​​the ultrasonic pre-welding to the area of ​​the electrode is 0.81. For example, both the laser final weld and the ultrasonic pre weld are elliptical in shape. The minor axis of the ellipse of the ultrasonic pre weld is b, and the major axis is a. The minor axis of the ellipse of the laser final weld is 0.32b, and the major axis is 0.72a. The area of ​​the pole is S1 = π*a*b, and the area of ​​the laser final weld is S2 = π*0.8a*0.4b. The size of a ranges from 1mm to 500mm, and the size of b ranges from 1mm to 400mm.

[0081] Specifically, to ensure the rationality of the laser final welding trajectory setting, the ratio between the trajectory perimeter of the laser final welding and the trajectory perimeter of the ultrasonic pre-welding is less than 1, that is, the trajectory perimeter of the laser final welding is smaller than that of the ultrasonic pre-welding. This results in higher processing and manufacturability, better current handling capacity, and better temperature rise control. For example, both the laser final welding and ultrasonic pre-welding are elliptical in shape. The minor semi-axis of the ellipse of the ultrasonic pre-welding is b, and the major semi-axis is a. The minor semi-axis of the ellipse of the laser final welding is 0.32b, and the major semi-axis is 0.72a. The trajectory perimeter of the ultrasonic pre-welding is L1 = 2π*b + 4(ab), and the trajectory perimeter of the laser final welding is L2 = 2π*b + 4(ab).

[0082] *0.32b+4(0.72a-0.32b), where the size range of a is 1mm-500mm and the size range of b is 1mm-400mm.

[0083] In this embodiment, the first solder area is determined based on the size and shape of the electrode post to ensure its rationality. Based on the first solder area, the tabs on the core pack are ultrasonically pre-welded according to the first solder area, reducing the interlayer gap between the tabs and making the tabs a tight whole. This reduces abnormalities such as incomplete welding that may occur during laser welding. The ultrasonically pre-welded tabs and the electrode post are then laser-welded according to the second solder area. Since the second solder area is smaller than the first solder area, it can be ensured that the tabs are completely attached to the electrode post. Under the premise of achieving welding stability, the current carrying capacity of the tabs is guaranteed, ensuring the rationality and maximization of the second solder area. This effectively improves the current carrying capacity at the connection between the tabs and the electrode post and reduces the temperature rise. Furthermore, the laser welding method forms a complete path between the tabs and the electrode post, greatly improving the battery yield.

[0084] In one example, such as Figure 3 The diagram shows a comparison of the tensile strength of batteries with two laser-welded shapes. The experimental group is the elliptical shape described in this embodiment, while the control group is a double-line shape, type II. The welding energy is 3900W, the welding speed is 200mm / s, and the number of layers is 70. Figure 4 It is evident that the peel strength of the experimental group is higher than that of the control group, and the weld of the experimental group is superior to that of the control group.

[0085] In one example, such as Figure 4 The diagram shows a comparison of the tested internal resistance (ACR1) of batteries with two laser-welded shapes. The experimental group is the elliptical shape used in this embodiment, while the control group is a bilinear shape. Figure 4 It can be seen that the ACR1 level in the experimental group decreased by 0.0267 milliohms compared to the control group, representing a decrease of 11.42%.

[0086] In one example, such as Figure 5The diagram shows a comparison of the discharge temperature rise of batteries with two laser-welded shapes. The experimental group is the elliptical shape used in this embodiment, while the control group is a bilinear shape. Figure 5 It can be seen that the discharge temperature rise of the experimental group is better than that of the control group by 1℃-1.5℃.

[0087] This application also provides a battery, such as... Figure 6 The diagram illustrates the welding connection between the tabs and terminals in a battery. The battery includes a core pack and a cover plate. The core pack includes tabs, and the cover plate includes terminals. The tabs include multiple layers of positive tabs 10 and multiple layers of negative tabs 20. The multiple layers of positive tabs 10 and negative tabs 20 are ultrasonically pre-welded. The tabs and terminals are then laser-welded; for example, the ultrasonically pre-welded multiple layers of positive tabs 10 are laser-welded to the positive terminal, and the ultrasonically pre-welded multiple layers of negative tabs 20 are laser-welded to the negative terminal. In this embodiment, the tabs and terminals are welded together using the above-described welding method, resulting in a connected cover plate and core pack.

[0088] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0089] In practice, each of the above units or structures can be implemented as an independent entity or can be arbitrarily combined to be implemented as the same or several entities. For the specific implementation of each of the above units or structures, please refer to the previous method embodiments, which will not be repeated here.

[0090] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A welding method, characterized in that, The method includes: The tabs on the core package are ultrasonically pre-welded according to the first solder mark area to form ultrasonically pre-welded tabs, wherein the first solder mark area is determined according to the size and shape of the pole post; Laser welding is performed on the ultrasonic pre-welded tab and the electrode post according to the second solder area to complete the connection between the tab and the electrode post. The ratio of the second solder area to the first solder area is less than 1. The ratio of the second solder area to the first solder area is determined based on the overcurrent and temperature rise of the battery. The method further includes: Based on the shape of the electrode post, determine the preset adjustment coefficient corresponding to the shape of the electrode post; The dimensions of the pole are adjusted according to the preset adjustment coefficient to obtain the adjusted dimensions; The first solder area is obtained based on the adjusted dimensions.

2. The welding method according to claim 1, characterized in that, The pole post is square, circular, or elliptical in shape, and the corresponding dimensions of the pole post are length a, width b, radius r, minor axis c, and major axis d.

3. The welding method according to claim 2, characterized in that, include: If the pole post is square in shape, then the length a is adjusted according to the first preset adjustment coefficient.

1. Adjustments are made to obtain the adjusted length, where 0 < 1<1; The width b is adjusted according to the second preset coefficient.

2. Adjust the width to obtain the adjusted width, where 0 < 2 < 1; The first solder area is determined based on the adjusted length and the adjusted width.

4. The welding method according to claim 3, characterized in that, 0.7< 1<0.9； 0.3< 2<0.5。 5. The welding method according to claim 2, characterized in that, include: If the pole is circular, then the radius r is adjusted according to a third preset coefficient.

3. Adjustments are made to obtain the adjustment radius, where 0 < 3 < 1; The area of ​​the first solder mark is determined based on the adjusted radius.

6. The welding method according to claim 5, characterized in that, 0.75< 3<0.9。 7. The welding method according to claim 2, characterized in that, include: If the shape of the pole post is elliptical, the minor semi-axis c is adjusted according to the fourth preset adjustment coefficient.

4. Make adjustments to obtain the adjusted short half-axis, where 0 < 4<1; The major semi-axis d is adjusted according to the fifth preset adjustment coefficient.

5. Make adjustments to obtain the adjusted major semi-axis, where 0 < 5 < 1; The first solder area is determined based on the adjusted short half-axis and the adjusted long half-axis.

8. The welding method according to claim 7, characterized in that, 0.85< 4<0.95；0.85< 5<0.95。 9. The welding method according to any one of claims 1-8, characterized in that, The ratio of the second solder area to the first solder area is And 0.6 < <0.

8.

10. The welding method according to any one of claims 1-8, characterized in that, Before performing ultrasonic pre-welding on the tabs on the core package according to the first solder area, the method further includes: The closing size of the tab is determined based on the thickness of the core package; The tabs are folded and pressed together according to the stated folding dimensions.

11. The welding method according to claim 10, characterized in that, The thickness of the core pack is 1mm-700mm, and the folded-up size is 1mm-500mm; or, The collapsible dimension is less than or equal to the thickness of the core package.

12. The welding method according to claim 10, characterized in that, The ratio of the collapsible size to the thickness of the core package is 1 / 5 to 1.

13. The welding method according to claim 10, characterized in that, The ratio of the collapsible size to the thickness of the core package is 1 / 4 to 5 / 7.

14. The welding method according to any one of claims 1-8, characterized in that, The step of laser welding the ultrasonic pre-welded tab to the electrode post according to the second weld area includes: Obtain the preset welding shape for laser welding; The laser welding trajectory is determined based on the second weld area and the preset welding shape; The ultrasonic pre-welded tab and the electrode post are laser welded according to the laser welding trajectory.

15. The welding method according to any one of claims 1-8, characterized in that, The ratio of the area of ​​the first solder mark to the area of ​​the pole post is greater than or equal to 0.32 and less than or equal to 0.81; And / or, the ratio between the perimeter of the trajectory corresponding to the laser welding and the perimeter of the trajectory corresponding to the ultrasonic pre-welding is less than 1.

16. A battery, characterized in that, The device includes a core package and a cover plate, wherein the core package includes a tab, the cover plate includes a post, and the tab and the post are connected by a welding method as described in any one of claims 1 to 15.

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