Welding method for multi-layer tab, and battery assembly

Abstract

A welding method for a multi-layer tab, and a battery assembly. The welding method for a multi-layer tab is used for welding a multi-layer tab (1) to an adapter sheet (2), the multi-layer tab (1) comprising a first edge (11) connected to a battery cell (4) and a second edge (12) arranged opposite the first edge. The welding method for a multi-layer tab comprises: placing at least part of the multi-layer tab (1) on the adapter sheet (2), wherein the second edge (12) is located on the adapter sheet (2); and using a laser (5) to melt the second edge (12), such that the multi-layer tab and the adapter sheet are fixed together by means of welding, and form a weld mark area (6) having a lap joint (3), wherein part of the lap joint (3) is located on the multi-layer tab (1), and the remaining part is located on the adapter sheet (2). In the welding method, the loose multi-layer tab is directly welded to the adapter sheet simply by means of making laser penetrate the multi-layer tab, without the need for ultrasonic pre-welding and tab cutting and shaping, thereby solving the technical problem of the risk of a short circuit caused by foreign matters such as debris and burrs entering a battery core during the process of welding in conventional welding methods, and significantly improving the processing yield and product safety performance of a battery assembly.

Description

A welding method of a multi-layer tab and a battery assembly

[0001] This application is based on and claims priority to Chinese Patent Application No. 202411342631.1, filed on September 25, 2024, the entire contents of which are incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application belongs to the technical field of battery manufacturing, and relates to a welding method of a multi-layer tab and a battery assembly. BACKGROUND

[0003] In the production and manufacturing process of the battery, the welding of the multi-layer tab and the cover plate is an important process in the battery production process and has an important connecting function. In the traditional welding process, the multi-layer tab is first ultrasonically welded for pre-welding, then the excess tab in the tower-shaped area is cut and shaped, and finally the cut multi-layer tab is welded with the cover plate. This method has a complex manufacturing process, and the ultrasonic pre-welding and the subsequent tab cutting and shaping process are prone to generate foreign matters such as debris and burrs, increasing the risk of short circuit caused by foreign matters entering the pole core. Moreover, the ultrasonic welding machine is expensive, increasing the manufacturing cost. SUMMARY

[0004] Therefore, the present application provides a welding method of a multi-layer tab and a battery assembly, which solves the technical problem of the risk of short circuit caused by foreign matters such as debris and burrs in the welding process entering the pole core in the traditional welding method.

[0005] In order to solve the above problems, according to one aspect of the present application, an embodiment of the present application provides a welding method of a multi-layer tab for welding the multi-layer tab on a adapter piece, the multi-layer tab comprising a first side connected with a battery cell and a second side disposed opposite to the first side, the welding method of the multi-layer tab comprising:

[0006] S1, placing at least part of the multi-layer tab on the adapter piece; wherein the second side is located on the adapter piece;

[0007] S2, melting the second side using a laser to achieve welding and fixation of the multi-layer tab and the adapter piece, and to form a welding mark area with a lap joint; wherein a part of the lap joint is located on the multi-layer tab and the remaining part is located on the adapter piece.

[0008] In some embodiments, the melting of the second side using a laser in S2 comprises:

[0009] The light outputted from the laser fiber is converted from divergent light to parallel light; the parallel light is offset; the offset parallel light is focused and welded, so that the laser focus point moves on the multi-layered tab according to the required requirements.

[0010] In some embodiments, the laser focus point moves on the multi-layered tab according to the required requirements, including:

[0011] By using a single-mode laser, a galvanometer scanning filling is adopted, a preset welding pattern is filled, a scanning welding is performed by controlling the galvanometer motor according to the preset track, the focused light beam scans back and forth between the edge of the multi-layered tab and the position of the adapter sheet, and small holes are formed on the surface of the multi-layered tab and the adapter sheet.

[0012] In some embodiments, the welding pattern of the galvanometer scanning filling includes a rectangular contour, and the contour has a plurality of fixed-interval filling lines, which are diagonal lines or straight lines.

[0013] And / or the width of the contour is 3-8mm, the length of the contour is 5-50mm, the interval of the filling lines is 0.05-0.5mm, the scanning speed of the galvanometer is 200-500mm / s, the welding power of the laser is 500-4000W, and the defocusing amount is ±3mm.

[0014] In some embodiments, the S1 includes placing at least part of the multi-layered tab on the adapter sheet, specifically:

[0015] First, the adapter sheet is placed on the lower pressing plate, then at least part of the multi-layered tab is placed on the adapter sheet, and finally the upper pressing plate is placed on the multi-layered tab for pressing the periphery of the second edge.

[0016] In some embodiments, the S2 includes using laser to melt the second edge, specifically:

[0017] The laser passes through the laser through hole on the upper pressing plate for welding, and a protective gas is introduced into the upper pressing plate; wherein the flow direction of the protective gas is opposite to the welding direction.

[0018] In some embodiments, the flow rate of the protective gas is between 10-50L / min;

[0019] And / or the protective gas is nitrogen or argon.

[0020] In some embodiments, the distance between the welding mark area close to one side of the upper pressing plate and the upper pressing plate is 0.5mm-3mm;

[0021] And / or the distance between the side of the welding mark area close to the lower pressing plate and the lower pressing plate is 0.5mm-3mm.

[0022] In some embodiments, the length of the welding mark area is 5-50mm, and the width is 3-8mm; and a circular arc-shaped molten pool is formed on the width side of the welding mark area.

[0023] According to another aspect of the present application, the embodiments of the present application provide a battery assembly, which comprises a battery tab and a cover plate, the battery tab is connected through the adapter sheet and the cover plate, and the battery tab is welded on the adapter sheet through the welding method.

[0024] Compared with the prior art, the welding method of the multi-layer tab of the present application has at least the following beneficial effects:

[0025] The welding method of the multi-layer tab provided by the present application is used for welding a multi-layer tab on an adapter sheet, the multi-layer tab comprises a first side connected with a battery cell and a second side arranged opposite to the first side, and the welding method of the multi-layer tab comprises: placing at least part of the multi-layer tab on the adapter sheet; wherein the second side is located on the adapter sheet; melting the second side using a laser, so that the multi-layer tab and the adapter sheet are welded and fixed, and a welding mark area with a lap joint is formed; wherein part of the lap joint is located on the multi-layer tab, and the remaining part is located on the adapter sheet.

[0026] The welding method of the multi-layer tab provided by the present application is different from the welding of the conventional multi-layer tab and the adapter sheet. During welding, the welding position is in the ultrasonic welding area inside the tab. After welding, all the molten pools are located on the multi-layer tab, and do not directly act on the adapter sheet, but are fused with the adapter sheet through the way of overlay welding. The present application directly penetrates the multi-layer tab through the laser, and directly welds the loose multi-layer tab and the adapter sheet together, without using ultrasonic pre-welding and tab cutting and shaping. The technical problem of the risk of short circuit caused by foreign matters such as debris and burrs in the welding process entering the tab core in the conventional welding method is solved, and the processing yield and product safety performance are significantly improved.

[0027] The battery assembly provided by the present application is designed based on the welding method of the multi-layer tab described above, and the beneficial effects thereof are referred to the beneficial effects of the welding method of the multi-layer tab described above, which will not be repeated here.

[0028] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will be described in detail with the preferred embodiments of the present application and with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0030] Fig. 1 is a cooperation diagram of the battery cell, the multi-layer tab and the adapter plate in a multi-layer tab welding method according to an embodiment of the present application;

[0031] Fig. 2 is a schematic diagram of the lap joint formed after the multi-layer tab and the adapter plate are welded in a multi-layer tab welding method according to an embodiment of the present application;

[0032] Fig. 3 is a schematic diagram of the cooperation between the multi-layer tab and the adapter plate when the multi-layer tab is in a cut state in a multi-layer tab welding method according to an embodiment of the present application;

[0033] Fig. 4 is an enlarged view of the cooperation between the multi-layer tab and the adapter plate in Fig. 3;

[0034] Fig. 5 is a schematic diagram of the cooperation between the multi-layer tab and the adapter plate when the multi-layer tab is in a staggered state in a multi-layer tab welding method according to an embodiment of the present application;

[0035] Fig. 6 is an enlarged view of the cooperation between the multi-layer tab and the adapter plate in Fig. 5;

[0036] Fig. 7 is a flowchart of a multi-layer tab welding method according to an embodiment of the present application.

[0037] Wherein:

[0038] 1, multi-layer tab; 11, first side; 12, second side; 2, adapter plate; 3, lap joint; 4, battery cell; 5, laser beam; 6, welding mark area. DETAILED DESCRIPTION

[0039] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined application purposes, the specific embodiments, structures, features and effects according to the present application will be described in detail below in combination with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0040] In the description of the present application, it is necessary to make it clear that the terms "first", "second" and the like in the description and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence; the terms "vertical", "transverse", "longitudinal", "front", "back", "left", "right", "up", "down", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not mean that the devices or elements referred to must have a particular orientation or position, so it cannot be understood as a limitation on the present application.

[0041] In the description of the present application, it is necessary to make it clear that the terms "installation", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] Embodiment 1

[0043] The present embodiment provides a welding method for a multi-layer tab, as shown in FIGS. 1-6, for welding a multi-layer tab 1 on a adapter tab 2, the multi-layer tab 1 comprising a first edge 11 connected with a battery cell 4, a second edge 12 disposed opposite to the first edge 11, the welding method for the multi-layer tab comprising:

[0044] S1, placing at least part of the multi-layer tab 1 on the adapter tab 2; wherein the second edge 12 is located on the adapter tab 2;

[0045] S2, melting the second edge 12 using laser, so that the multi-layer tab 1 and the adapter tab 2 are welded and fixed, and a welding mark area 6 with a lap joint 3 is formed; wherein part of the lap joint 3 is located on the multi-layer tab 1, and the rest is located on the adapter tab 2.

[0046] Specifically, the adapter tab 2 is a structure on the battery cover plate, which includes pole, retainer, adapter tab 2, sealing ring and other components. Generally, the positive pole and the negative pole are directly connected with the adapter tab 2, and the connection of the multi-layer tab 1 and the cover plate is realized by laser direct welding of the multi-layer tab 1 and the adapter tab 2. The aluminum tab needs to be welded on the aluminum adapter tab, and the copper tab is welded on the copper adapter tab. The length of the adapter tab 2 is 5-100mm, the width is 5-60mm, and the thickness is 0.5-2mm.

[0047] In the embodiment, the multi-layer tabs 1 are made of different materials and thicknesses according to the connection of the positive and negative electrodes of the battery. The tabs connected to the positive cover plate of the battery are aluminum tabs, the number of layers is 50-120, and the thickness of a single layer of aluminum tab is 0.01-0.02 mm. The tabs connected to the negative cover plate of the battery are copper tabs, the number of layers is 50-120, and the thickness of a single layer of copper tab is 0.004-0.01 mm.

[0048] The multi-layer tabs 1 in step 1 of the embodiment refer to the multi-layer tabs stacked in order. The lap joint 3 refers to the multi-layer tabs 1 on the adapter piece 2 before welding. During welding, the welding position is located at the intersection of the edge of the multi-layer tab 1 and the adapter piece 2. After welding, part of the molten pool is located at the edge of the multi-layer tab 1, and the other part is located on the adapter piece 2. This welding method is called lap welding, and the lap structure 3 is formed after lap welding.

[0049] The welding method of the multi-layer tab provided in the embodiment is different from the conventional welding of the multi-layer tab and the adapter piece. During welding, the welding position is in the ultrasonic welding area inside the tab. After welding, all the molten pools are located on the multi-layer tab, and there is no direct action on the adapter piece, but the molten pools penetrate the multi-layer tab 1 and the adapter piece 2 and fuse through the overlay welding.

[0050] The welding method of the multi-layer tab provided in the embodiment directly penetrates the multi-layer tab with laser to weld the loose multi-layer tab 1 and the adapter piece 2 together without using ultrasonic pre-welding and tab cutting and shaping. The technical problem of the risk of short circuit caused by foreign matter such as debris and burrs in the traditional welding process is solved, and the processing yield and product safety performance are significantly improved.

[0051] In specific embodiments, the laser melting of the second edge 12 in S2 includes converting the light output by the laser fiber into parallel light from divergent light, offsetting the parallel light, and welding after focusing the offset parallel light, so that the laser focal point moves on the multi-layer tab 1 as required.

[0052] Specifically, in one of the embodiments, a galvanometer system is used to collimate and focus the laser beam 5 for welding. The galvanometer system includes a laser collimation module, a scanning galvanometer module, and a laser focusing module. The collimation module is a device that converts the light output by the laser fiber from divergent light into parallel light. The scanning galvanometer deflects the light beam by controlling the high-precision motors in the X / Y direction. The focusing module finally focuses the deflected parallel light, so that the laser focal point with a certain power density moves on the material as required.

[0053] In specific embodiments, the laser focus point is moved on the multi-layer tab 1 as required, including: through a single-mode laser, using a galvanometer scanning filling, according to a pre-set welding pattern, scanning and welding according to a pre-set trajectory by controlling the galvanometer motor, and the focused light beam scans back and forth between the edge of the multi-layer tab 1 and the position of the adapter sheet 2, while forming a small hole on the surface of the multi-layer tab 1 and the adapter sheet 2.

[0054] Specifically, the laser uses a single-mode laser, the mode center fiber core diameter is 20um, and the annular fiber core diameter is 200um. The welding method uses a galvanometer scanning filling, and the welding pattern to be welded is pre-set in CAD or welding software. The focused light beam scans back and forth quickly between the edge of the tab and the position of the adapter sheet, while forming a small hole on the surface of the material.

[0055] This small hole welding method can produce a stable molten pool to realize the welding of the foil and the cover plate lead-out sheet. Because of the scanning filling method, the laser does not stay at the edge of the foil for a long time, thereby avoiding the phenomenon that the foil deforms and cannot form a stable molten pool due to long-time heat input. Compared with the traditional method of one-time heat conduction welding and two-time deep penetration welding, the method provided in the embodiment can realize the welding of the foil and the cover plate in one-time welding, and has higher efficiency.

[0056] In specific embodiments, the welding pattern of the galvanometer scanning filling includes a rectangular contour, and the contour has a plurality of filling lines with fixed intervals, and the filling lines are diagonal lines or straight lines.

[0057] In specific embodiments, the width of the contour is 3-8mm, the length of the contour is 5-50mm, the interval of the filling lines is 0.05-0.5mm, the scanning speed of the galvanometer is 200-500mm / s, and the welding power of the laser is 500-4000W, and the defocusing amount is ±3mm.

[0058] In specific embodiments, the step of placing at least part of the multi-layer tab 1 on the adapter sheet 2 in S1 is as shown in FIG. 7, specifically: first, placing the adapter sheet 2 on the lower pressing plate, then placing at least part of the multi-layer tab 1 on the adapter sheet 2, and finally placing the upper pressing plate on the multi-layer tab 1 for pressing the periphery of the second edge.

[0059] Specifically, the multi-layer tab 1 and the adapter sheet 2 are provided in a stacked and aligned manner, the adapter sheet 2 is first placed on the lower pressing plate, then the multi-layer tab 1 is placed on the adapter sheet 2, and the upper pressing plate is used to press the welding position around to ensure that there is no gap between the multi-layer tab 1 and the adapter sheet 2 of the cover plate.

[0060] In specific embodiments, the second edge is melted by laser in S2, specifically, laser welding is performed through the laser through hole on the upper pressing plate, and a protective gas is introduced into the upper pressing plate; wherein the flow direction of the protective gas is opposite to the welding direction.

[0061] The protective gas during welding forms a stable flow in the welding mark area 6 and the laser through hole, which can effectively prevent the surface of the welded joint from being oxidized, inhibit spatter, and stabilize the welding keyhole. The protective gas is mainly high-purity nitrogen or argon, which can obtain a better welding appearance.

[0062] In addition, during welding, the upper pressing plate has a laser through hole, when the upper pressing plate is pressed on the multi-layer tab 1, the welding part of the multi-layer tab 1 and the adapter tab 2 can be exposed through the laser through hole, and the laser emits laser towards the laser through hole to form the welding mark area 6.

[0063] In addition, the laser welds the edge position of the multi-layer tab 1 to the adapter tab 2 through the welding mark area 6, and the direction is from left to right, which needs to be opposite to the direction of the stable flow formed by the protective gas, which can effectively prevent the smoke and dust impurities generated during welding from polluting the area that has not been welded, ensure the cleanliness of the subsequent welding area, and improve the yield during welding.

[0064] In specific embodiments, the flow rate of the protective gas is between 10-50 L / min; if the flow rate is too small, it cannot carry away the plasma and smoke and dust impurities generated during welding, the light blocking causes the welding keyhole to lose stability, the fusion depth fluctuates greatly, and the smoke and dust impurities also adhere to the weld area, affecting the joint performance and weld appearance; if the flow rate is too large, the protective gas will significantly reduce the temperature during welding, causing the time edge of the molten pool keyhole to be long, and the impact force of the protective gas on the molten pool during welding will affect the stability of the molten pool keyhole.

[0065] In specific embodiments, the protective gas is nitrogen or argon. The protective gas is generally mainly high-purity nitrogen or high-purity argon, and in some special cases, nitrogen and compressed air are mixed in different proportions.

[0066] In specific embodiments, the distance between the welding mark area 6 close to one side of the upper pressing plate and the upper pressing plate is 0.5-3 mm; and / or the distance between the welding mark area 6 close to one side of the lower pressing plate and the lower pressing plate is 0.5-3 mm.

[0067] The distance S between the welding mark area 6 and the upper pressing plate and the distance S between the welding mark area 6 and the lower pressing plate must be kept at 0.5 mm to 3 mm; in principle, the closer the distance, the better the pressing effect, but it is easy to block the laser beam 5, and if the distance is too far, the multi-layer tab 1 will be in the protective gas flow during welding, and the impact force of the laser beam 5 during welding will cause the multi-layer tab 1 to have gaps or deform, affecting the welding effect. After many verifications, the distance between 0.5 mm and 3 mm has the best pressing effect and will not affect the welding effect.

[0068] In specific embodiments, the length L of the welding mark area 6 is 5-50 mm, and the width W is 3-8 mm; wherein the length direction is set according to the tab width, and a pressing position needs to be left. The width size is set according to the tower-shaped area after the tabs are gathered.

[0069] And a circular arc-shaped molten pool is formed on the width side of the welding mark area 6. Compared with penetration welding, the welding molten pool surface tension is more likely to obtain a stable molten pool, thereby overcoming the gap between the foils and achieving welding.

[0070] In the production process of square cell batteries, the tabs and the cover plate are currently welded using laser penetration welding. Due to the gap between the foils, the multi-layer tabs need to be pre-welded by ultrasonic wave first, and then the pre-welded tabs are welded to the cover plate by laser. At the same time, due to the existence of ultrasonic pre-welding, the excess tower-shaped area tabs need to be cut after ultrasonic pre-welding, so that a cutting and shaping process is added. This method is complicated and has a high defect rate; and the debris, burrs and other foreign matters generated by pre-welding and cutting increase the risk of short circuit of the battery. The welding method of the multi-layer tabs provided in the embodiment uses lap welding, which can realize direct welding of the foils and the cover plate, cancels the step of pre-welding the multi-layer tabs by ultrasonic wave, and does not need to consider the process of cutting the tabs, thereby greatly reducing the battery processing steps, increasing the battery capacity, improving the production and manufacturing efficiency, and reducing the production cost.

[0071] Embodiment 2

[0072] The embodiment provides a battery assembly, which comprises a battery tab 1 and a cover plate, the battery tab 1 is connected to the cover plate through the adapter piece 2, and the battery tab 1 is welded on the adapter piece 2 by the welding method in embodiment 1.

[0073] In summary, those skilled in the art can easily understand that the above-mentioned advantageous technical features can be freely combined and superimposed without conflict.

[0074] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application are still within the scope of the technical solutions of the present application.

Claims

1. A method for welding multi-layer tabs, used to weld multi-layer tabs onto an adapter plate, wherein the multi-layer tabs include a first side connected to a battery cell and a second side disposed opposite to the first side, characterized in that, The welding method of the multi-layer tab includes: S1, placing at least part of the multi-layer tab on the adapter tab; wherein the second edge is located on the adapter tab; S2, melting the second edge using laser to make the multi-layer tab and the adapter tab achieve welding fixation and form a welding mark area with a lap joint; wherein part of the lap joint is located on the multi-layer tab and the rest is located on the adapter tab.

2. The method of claim 1, wherein In S2, melting the second edge using laser includes: converting the light output by the laser fiber into parallel light from divergent light; offsetting the parallel light; and welding after focusing the offset parallel light, so that the laser focus point moves on the multi-layer tab as required.

3. The method of claim 2, wherein The laser focus point moves on the multi-layer tab as required, including: Through a single-mode laser, a galvanometer scanning filling is adopted to scan and weld according to a pre-set welding pattern by controlling the galvanometer motor to follow a pre-set trajectory, and the focused light beam scans back and forth between the edge of the multi-layer tab and the position of the adapter tab, while forming a small hole on the surface of the multi-layer tab and the adapter tab.

4. The method of claim 3, wherein The welding pattern of the galvanometer scanning filling includes a rectangular contour, and the contour has a plurality of fixed-interval filling lines, which are diagonal lines or straight lines. And / or the width of the contour is 3-8mm, the length of the contour is 5-50mm, the interval of the filling lines is 0.05-0.5mm, the scanning speed of the galvanometer is 200-500mm / s, the welding power of the laser is 500-4000W, and the defocusing amount of the laser is ±3mm.

5. The method of claim 1, wherein In S1, placing at least part of the multi-layer tab on the adapter tab specifically includes: First, place the adapter tab on the lower pressing plate, then place at least part of the multi-layer tab on the adapter tab, and finally place the upper pressing plate on the multi-layer tab to press the periphery of the second edge.

6. The method of claim 5, wherein In S2, melting the second edge using laser specifically includes: The laser passes through the laser through-hole on the upper pressing plate for welding, and at the same time, a protective gas is introduced into the upper pressing plate; wherein the flow direction of the protective gas is opposite to the welding direction.

7. The method of claim 6, wherein The flow rate of the protective gas is between 10-50L / min; And / or the protective gas is nitrogen or argon.

8. The method of claim 5, wherein The distance between the side of the welding mark area close to the upper pressing plate and the upper pressing plate is 0.5mm-3mm; And / or the distance between the side of the welding mark area close to the lower pressing plate and the lower pressing plate is 0.5mm-3mm.

9. The method of claim 1, wherein The length of the welding mark area is 5-50mm, and the width is 3-8mm; and a circular arc-shaped molten pool is formed on the width side of the welding mark area.

10. A battery assembly characterized by, The battery assembly includes a battery tab and a cover plate, the battery tab is connected through the adapter tab and the cover plate, and the battery tab is welded on the adapter tab by the welding method of any one of claims 1-9.

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