Tab structure of composite current collector and welding method thereof, battery, welding device

Abstract

The application relates to a tab structure of a composite current collector and a welding method, a battery, and a welding device thereof. The tab structure of the composite current collector comprises a composite current collector, the composite current collector comprises a first metal layer, a polymer macromolecule layer and a second metal layer which are arranged in a stack, and the surface of the first metal layer is provided with a tab welding area; a tab is connected with the tab welding area through a conductive welding part, the conductive welding part comprises a first solder part and a second solder part; the surface of the first metal layer is connected with the tab through the first solder part; at least part of the second solder part covers the second metal layer of the composite current collector, and at least part of the second solder part extends from the second metal layer of the composite current collector to the first metal layer along the thickness direction of the composite current collector, so that the composite current collector is connected with the tab through the second solder part. The tab structure can conduct the metal layers on both sides of the polymer macromolecule layer in the composite current collector, and improves the welding strength between the composite current collector and the tab.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a tab structure of a composite current collector, a welding method of the tab structure, a battery and a welding device. BACKGROUND

[0002] The composite current collector has been widely concerned because it can improve the energy density and safety of the lithium ion battery. However, the composite current collector is composed of a polymer macromolecular layer and metal layers arranged on both sides of the polymer macromolecular layer. In general, the polymer macromolecular layer in the composite current collector is not conductive itself, so the upper and lower metal layers of the composite current collector need to be welded with metal tabs to converge the current on the current collector. However, the traditional welding method for pure metal foil is not suitable for the new type of composite current collector.

[0003] In the prior art, the tab welding of the composite current collector includes ultrasonic welding, laser welding and pressure melting welding. The traditional ultrasonic spot welding method cannot realize the conduction of the upper and lower metal layers, and needs to be additionally connected and welded, which increases the process and the effect of the ultrasonic spot welding is general, which is easy to be false welding or through welding, and damages the base material. The temperature of laser welding is too high, which is not suitable for the welding of the composite current collector and the metal tab. The pressure melting welding has not been verified by the battery factory in a large amount, and the effect of multi-layer welding is better, which is quite different from the single-layer tab welding of the wound battery. The current ultrasonic rolling welding technology connects the upper and lower metal foils of the composite current collector, which can realize good tab welding. However, the current large rolling welding equipment is expensive, and the double-layer foil with overlapped tabs occupies a large space, which is not conducive to the improvement of the energy density of the battery. Therefore, the tab welding of the composite current collector still needs a better solution. SUMMARY

[0004] The present application provides a tab structure of a composite current collector and a welding method thereof, a battery and a welding device, which can realize the conduction of the metal layers on both sides of the polymer macromolecular layer in the composite current collector without introducing other processes, can improve the welding strength between the composite current collector and the tab, reduce the contact resistance of the battery, and thus reduce the temperature rise of the battery.

[0005] In a first aspect, the present application provides a tab structure of a composite current collector, comprising:

[0006] The composite current collector comprises a first metal layer, a polymer macromolecular layer and a second metal layer arranged in layers, and the surface of the first metal layer is provided with a tab welding area;

[0007] The tab is connected with the tab welding area through a conductive welding part, and the conductive welding part comprises a first solder part and a second solder part;

[0008] The first soldering part is connected between the surface of the first metal layer and the tab;

[0009] At least part of the second soldering part covers the second metal layer of the composite current collector, and at least part of the second soldering part extends from the second metal layer of the composite current collector to the first metal layer along the thickness direction of the composite current collector, so that the composite current collector and the tab are connected through the second soldering part.

[0010] In some embodiments, the length of the second soldering part extending from the second metal layer of the composite current collector to the first metal layer along the thickness direction of the composite current collector is 0.1 mm to 10 mm.

[0011] In some embodiments, the length of the second soldering part covering the second metal layer of the composite current collector is 0.1 mm to 10 mm.

[0012] In some embodiments, when the second soldering part extends from the second metal layer of the composite current collector to the first metal layer along the thickness direction of the composite current collector, the distance between the first soldering part and the second soldering part is 0 mm to 20 mm.

[0013] In some embodiments, the total length of the tab is 3 cm to 7 cm, and the length of the overlapping part of the tab and the composite current collector is 1 cm to 5 cm.

[0014] In some embodiments, the thickness of the first soldering part is ≤100 μm; and / or, the thickness of the second soldering part is ≤500 μm.

[0015] In a second aspect, the present application provides a welding method of the tab structure of the composite current collector according to the first aspect, and the method comprises the following steps:

[0016] Preparation of the first soldering material and the second soldering material, the first soldering material extending from the first soldering material outlet of the tab welding device, the second soldering material extending from the second soldering material outlet of the tab welding device, adjustment of the height and horizontal direction of the first soldering material outlet and / or the second soldering material outlet, so that the first soldering material outlet and the second soldering material outlet are located on the same horizontal line;

[0017] The composite current collector is arranged on the workbench of the tab welding device, and the tab welding area of the composite current collector is located between the first soldering material and the second soldering material along the height direction;

[0018] The tab is placed above the first soldering material, and a part of the tab overlaps the composite current collector;

[0019] The temperature of the welding head of the tab welding device is raised to a preset temperature, and the pressing device of the tab welding device is adjusted to drive the welding head to press downward and maintain a preset pressing force;

[0020] The pressing device is controlled to rise and separate from the composite current collector, thereby obtaining the composite current collector after the tab is welded.

[0021] In some embodiments, the length of the first solder material extending from the first solder outlet is 1-5 cm; and / or, the length of the second solder material extending from the second solder outlet is 0.2-2 cm.

[0022] In some embodiments, the first solder material and the second solder material comprise at least one of tin wire, tin sheet, solder paste, tin-lead alloy wire, tin-lead alloy sheet, tin-copper alloy wire, tin-copper alloy sheet, and flux.

[0023] In some embodiments, the length of the overlapping part of the tab and the composite current collector is 1-5 cm.

[0024] In some embodiments, the preset temperature of the welding head is 150-250°C.

[0025] In some embodiments, the pressing force P satisfies 0

[0026] In some embodiments, the holding time T of the pressing device after pressing satisfies 0

[0027] In some embodiments, the second solder material is laid flat on the workbench, and the first solder material extending from the first solder outlet is higher than the second solder material in the height direction.

[0028] In a third aspect, the application provides a battery comprising the tab structure of the composite current collector of the first aspect or the tab structure of the composite current collector welded by the welding method of the second aspect.

[0029] In a fourth aspect, the application provides a welding device for preparing the tab structure of the composite current collector of the first aspect, which comprises:

[0030] A base, the upper surface of the base is provided with a workbench, and a first solder outlet and a second solder outlet are respectively arranged on the opposite sides of the workbench, and the first solder outlet and the second solder outlet are adjustable in the horizontal direction and the height direction;

[0031] The application discloses a liftable pressing device connected with a welding head, which drives the welding head to press down and adjusts the pressing force and the holding time of the welding head.

[0032] In some embodiments, the pressing device is provided with a temperature adjusting device of the welding head.

[0033] In some embodiments, the pressing device comprises a lifting assembly connected with the base and a support connected with the lifting assembly and extending in the horizontal direction, and the end of the support is connected with the welding head; the lifting assembly drives the support to move up and down in the height direction.

[0034] In some embodiments, the first soldering part is movably connected with the lifting assembly and is arranged in parallel with the support, and the first soldering part does not interfere with the welding head when the welding head moves in the height direction.

[0035] The technical scheme of the application has at least the following beneficial effects:

[0036] The tab structure of the composite current collector provided by the application is connected with the tab welding area through the conductive welding part, the conductive welding part comprises a first soldering part and a second soldering part; the surface of the first metal layer is connected with the tab through the first soldering part; at least part of the second soldering part covers the second metal layer of the composite current collector, and at least part of the second soldering part extends from the second metal layer of the composite current collector to the first metal layer in the thickness direction of the composite current collector, so that the composite current collector is connected with the tab through the second soldering part. Tin has good conductivity, and the composite current collector and the tab are connected through the first soldering part and the second soldering part, so that the first metal layer and the second metal layer on both sides of the polymer layer in the composite current collector are connected in conduction without introducing other transfer foils, so as to ensure that the current can flow smoothly between the first metal layer and the second metal layer, thereby improving the overall performance of the battery; meanwhile, the welding strength between the tab and the composite current collector can be improved, the battery contact resistance can be reduced, and the battery temperature rise can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0037] The application will be further described below in combination with the drawings and examples.

[0038] Figure 1 The structure schematic view of the tab structure of the composite current collector provided by the application is shown in the figure;

[0039] Figure 2 The structure schematic view of the tab structure of the composite current collector provided by the application is shown in the figure;

[0040] Figure 3A structure diagram of a tab structure of a composite current collector provided for Embodiment 4 of the present application;

[0041] Figure 4 A structure diagram of a tab structure of a composite current collector provided for Embodiment 5 of the present application;

[0042] Figure 5 A welding device diagram of a tab structure of a composite current collector provided for Embodiment of the present application;

[0043] Figure 6 A diagram of various material points when welding a tab structure of a composite current collector provided for Embodiment of the present application;

[0044] Figure 7 A front (upper) structure diagram of a tab structure of a composite current collector after welding is completed, provided for Embodiment of the present application;

[0045] Figure 8 A back (lower) structure diagram of a tab structure of a composite current collector after welding is completed, provided for Embodiment of the present application;

[0046] Figure 9 A resistance test position diagram of a tab structure of a composite current collector provided for Embodiment of the present application.

[0047] The figure mark: 1-composite current collector, 11-first metal layer, 10-polymer macromolecular layer, 12-second metal layer, 2-tab, 3-conductive welding part, 31-first soldering part, 32-second soldering part, 4-welding device, 40-base, 41-workbench, 42-first soldering discharge part, 43-second soldering discharge part, 44-pressing device, 441-lifting assembly, 442-supporting piece, 45-welding head, 5-first soldering material, 6-second soldering material. DETAILED DESCRIPTION

[0048] In order to better understand the technical scheme of the present application, the embodiments of the present application are described in detail below with reference to the drawings.

[0049] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0050] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0051] It should be noted that the term "and / or" used herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0052] In a first aspect, the application provides a tab structure of a composite current collector, referring to Figures 1-4 The structure of the tab structure of the composite current collector is shown in the structure diagram, which comprises:

[0053] The composite current collector 1 comprises a first metal layer 11, a polymer high molecular layer 10 and a second metal layer 12 arranged in a stack, and the surface of the first metal layer 11 is provided with a tab welding area;

[0054] The tab 2 is connected with the tab welding area through a conductive welding part 3, and the conductive welding part 3 comprises a first solder part 31 and a second solder part 32;

[0055] The surface of the first metal layer 11 is connected with the tab 2 through the first solder part 31;

[0056] At least part of the second solder part 32 covers the second metal layer 12 of the composite current collector 1, and at least part of the second solder part 32 extends from the second metal layer 12 of the composite current collector 1 to the first metal layer 11 along the thickness direction of the composite current collector 1, so that the composite current collector 1 and the tab 2 are connected through the second solder part 32.

[0057] In the above scheme, the tab 2 is connected with the tab welding area through a conductive welding part 3, and the conductive welding part 3 comprises a first solder part 31 and a second solder part 32; the surface of the first metal layer 11 is connected with the tab 2 through the first solder part 31; at least part of the second solder part 32 covers the second metal layer 12 of the composite current collector 1, and at least part of the second solder part 32 extends from the second metal layer 12 of the composite current collector 1 to the first metal layer 11 along the thickness direction of the composite current collector 1, so that the composite current collector 1 and the tab 2 are connected through the second solder part 32. Tin has good conductivity, and by connecting the composite current collector 1 and the tab 2 through the first solder part 31 and the second solder part 32, the first metal layer 11 and the second metal layer 12 on both sides of the polymer high molecular layer 10 in the composite current collector can be connected without introducing other transfer foils, so as to ensure smooth flow of current between the first metal layer 11 and the second metal layer 12, thereby improving the overall performance of the battery; at the same time, the welding strength between the tab 2 and the composite current collector 1 can be improved, and the battery contact resistance can be reduced, thereby reducing the battery temperature rise.

[0058] In some embodiments, the second soldering part 32 extends from the second metal layer 12 of the composite current collector 1 to the first metal layer 11 along the thickness direction of the composite current collector 1, and the length is 0.1mm-10mm, specifically 0.1mm, 0.5mm, 1mm, 2mm, 3mm, 5mm, 6mm, 8mm or 10mm, and of course, it can also be other values within the above range, which is not limited here. It can be understood that when the length of the second soldering part 32 extending from the second metal layer 12 of the composite current collector 1 to the first metal layer 11 along the thickness direction of the composite current collector 1 is within the above range, it can ensure that the second soldering part 32 and the tab 2 have sufficient contact area, thereby reducing the contact resistance, improving the current transmission efficiency, and facilitating the conduction of the first metal layer 11 and the second metal layer 12 on both sides of the polymer macromolecular layer 10 in the composite current collector 1. It can also improve the welding strength between the second soldering part 32 and the tab 2, and reduce the risk of the tab 2 falling off or breaking from the composite current collector 1 in use.

[0059] In some embodiments, the second soldering part 32 covers the second metal layer 12 of the composite current collector 1, and the length is 0.1mm-10mm, specifically 0.1mm, 0.5mm, 1mm, 2mm, 3mm, 5mm, 6mm, 8mm or 10mm, and of course, it can also be other values within the above range, which is not limited here. It can be understood that when the length of the second soldering part 32 covering the second metal layer 12 of the composite current collector 1 is within the above range, it can reduce the contact resistance between the second soldering part 32 and the composite current collector 1, increase the current transmission efficiency, and thus ensure that the current can flow smoothly between the first metal layer 11 and the second metal layer 12.

[0060] In some embodiments, when the second soldering part 32 extends from the second metal layer 12 of the composite current collector 1 to the first metal layer 11 along the thickness direction of the composite current collector 1, the distance between the first soldering part 31 and the second soldering part 32 is 0mm-20mm, specifically 0mm, 5mm, 10mm, 15mm or 20mm, and of course, it can also be other values within the above range, which is not limited here. It can be understood that if the distance between the first soldering part 31 and the second soldering part 32 is greater than 20mm, the transmission path of the current is longer, the resistance increases, thereby increasing the difficulty of the current transmission between the first soldering part 31 and the second soldering part 32 in the first metal layer 11 and the second metal layer 12, which is not conducive to the conduction of the first metal layer 11 and the second metal layer 12 on both sides of the polymer macromolecular layer 10 in the composite current collector 1.

[0061] In some embodiments, please refer to Figure 2 and Figure 3, the distance between the first soldering part 31 and the second soldering part 32 is 0 mm. It can be understood that the first soldering part 31 and the second soldering part 32 are formed by melting and welding of the first soldering material and the second soldering material, and in the welding process, the first soldering material and the second soldering material flow and mix together in a molten state, and finally the first soldering part 31 and the second soldering part 32 are welded to form a whole, at this time the distance between the first soldering part 31 and the second soldering part 32 is 0 mm.

[0062] In some embodiments, the total length of the tab 2 is 3 cm to 7 cm, and can be 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, 6 cm or 7 cm, and can also be other values within the above range, which are not limited herein. It can be understood that the total length of the tab 2 within the above range can ensure that the tab 2 has sufficient contact area with the composite current collector 1, increase the mechanical strength of the welding position of the tab 2 and the composite current collector 1, reduce the risk of the tab 2 falling off or breaking from the composite current collector 1 in use, and effectively reduce the contact resistance, ensure smooth transmission of the current, and reduce energy loss, thereby improving the performance of the battery.

[0063] In some embodiments, the length of the overlapping part of the tab 2 and the composite current collector 1 is 1 cm to 5 cm, and can be 1 cm, 1.5 cm, 2 cm, 3 cm, 4 cm, 4.5 cm or 5 cm, and can also be other values within the above range, which are not limited herein. It can be understood that the length of the overlapping part of the tab 2 and the composite current collector 1 within the above range can ensure that there is sufficient contact area between the tab 2 and the conductive welding part 3, thereby improving the welding strength between the tab 2 and the composite current collector 1, and reducing the resistance between the tab 2 and the composite current collector 1, ensuring that the current can be smoothly transmitted through the conductive welding part 3, thereby facilitating the conduction of the first metal layer 11 and the second metal layer 12 on both sides of the polymer layer 10 in the composite current collector 1.

[0064] In some embodiments, the first metal layer 11 and the second metal layer 12 comprise a copper layer and / or an aluminum layer.

[0065] In some embodiments, the thickness of the first metal layer 11 is 0.5 μm to 2 μm, and can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm or 2 μm, and can also be other values within the above range, which are not limited herein.

[0066] In some embodiments, the second metal layer 12 has a thickness of 0.5-2 μm, specifically 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm or 2 μm, or other values within the range, which are not limited herein.

[0067] In some embodiments, the polymer macromolecular layer 10 comprises at least one of a polyethylene terephthalate film layer (PET film layer), a polypropylene film layer (PP film layer), and a polyimide film layer (PI film layer).

[0068] In some embodiments, the polymer macromolecular layer 10 has a thickness of 1-10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or other values within the range, which are not limited herein.

[0069] In some embodiments, the tab 2 comprises at least one of copper, aluminum, nickel, copper-aluminum alloy, copper-nickel alloy, aluminum-nickel alloy, or copper-aluminum-nickel alloy.

[0070] In some embodiments, the tab 2 has a thickness of ≤1 mm, specifically 1 mm, 0.9 mm, 0.8 mm, 0.6 mm, 0.5 mm or 0.3 mm, or other values within the range, which are not limited herein. It is understood that the thickness of the tab 2 within the range can reduce the resistance and improve the current transmission efficiency, can provide sufficient strength to ensure that the tab 2 is not easily deformed or broken during welding and use, and can ensure the welding quality, which is conducive to improving the welding strength between the tab 2 and the composite current collector 1.

[0071] In some embodiments, the first soldering part 31 has a thickness of ≤100 μm, specifically 100 μm, 99 μm, 98 μm, 80 μm, 70 μm, 65 μm, 50 μm, 20 μm, 30 μm or 10 μm, or other values within the range, which are not limited herein. It is understood that the thickness of the first soldering part 31 within the range can improve the welding strength between the tab 2 and the composite current collector 1, reduce the risk of the tab 2 falling off from the composite current collector 1 during use, and can also provide good electrical conductivity, which is conducive to ensuring smooth flow of current between the composite current collector 1 and the tab 2. Preferably, the thickness of the first soldering part 31 is 20-40 μm.

[0072] In some embodiments, the thickness of the second soldering part 32 is ≤500 μm, specifically 500 μm, 490 μm, 450 μm, 400 μm, 350 μm, 300 μm, 200 μm, 100 μm or 50 μm, etc., and of course can also be other values within the above range, which is not limited herein. It can be understood that the thickness of the second soldering part 32 is within the above range, on the one hand, it is beneficial to improve the welding strength between the tab 2 and the composite current collector 1, and reduce the risk of the tab 2 falling off from the composite current collector 1 in use; on the other hand, it is beneficial to reduce the contact resistance between the second soldering part 32 and the composite current collector 1, and improve the transmission efficiency of the current. Preferably, the thickness of the second soldering part 32 is 50 μm-100 μm.

[0073] In a second aspect, the application provides a welding method of the tab structure of the composite current collector described in the first aspect, the method comprising the following steps:

[0074] In step S100, the first soldering material 5 and the second soldering material 6 are prepared, the first soldering material 5 is stretched out from the first soldering outlet part 42 of the tab welding device, the second soldering material 6 is stretched out from the second soldering outlet part 43 of the tab welding device, and the height and horizontal direction of the first soldering outlet part 42 and / or the second soldering outlet part 43 are adjusted so that the first soldering outlet part 42 and the second soldering outlet part 43 are on the same horizontal line;

[0075] In step S200, the composite current collector 1 is arranged on the workbench 41 of the tab welding device, and the tab welding area of the composite current collector 1 is located between the first soldering material 5 and the second soldering material 6 in the height direction;

[0076] In step S300, the tab 2 is grabbed and placed above the first soldering material 5, and a part of the tab 2 overlaps the composite current collector 1;

[0077] In step S400, the temperature of the welding head 45 of the tab welding device is raised to a preset temperature, and the pressing device 44 of the tab welding device is adjusted, the pressing device 44 drives the welding head 45 to press down and maintain a preset pressing pressure;

[0078] In step S500, the pressing device 44 is controlled to rise and separate from the composite current collector 1, and the composite current collector after welding the tab is obtained.

[0079] In the above scheme, by using the welding device of the tab structure of the composite current collector provided in the present application to weld the tab structure of the composite current collector, the welding efficiency is high, and the soldering method is mature, which can ensure the consistency of the battery; by adjusting the temperature and the pressing pressure of the welding head of the tab welding device, the first soldering material and the second soldering material can be melted and solidified to connect the composite current collector and the tab, so that the composite current collector does not need to be connected to a pure metal foil, and the metal layers on both sides of the polymer molecular layer in the composite current collector can be connected, and the welding is simple and efficient, which can be adapted to the production of traditional foil batteries.

[0080] In step S100, the first soldering material 5 and the second soldering material 6 are prepared, the first soldering material 5 extends from the first soldering outlet 42 of the tab welding device, the second soldering material 6 extends from the second soldering outlet 43 of the tab welding device, and the height and the horizontal direction of the first soldering outlet 42 and / or the second soldering outlet 43 are adjusted so that the first soldering outlet 42 and the second soldering outlet 43 are on the same horizontal line.

[0081] In some embodiments, the length of the first soldering material 5 extending from the first soldering outlet 42 is 1cm-5cm, which can be 1cm, 2.5cm, 3cm or 5cm, and can also be other values within the above range, which is not limited here. It can be understood that the length of the first soldering material 5 extending from the first soldering outlet 42 is within the above range, which is beneficial to control the welding area of the first soldering part 31, thereby being beneficial to improve the welding strength between the tab 2 and the composite current collector 1 and reduce the contact resistance between the tab 2 and the composite current collector 1.

[0082] In some embodiments, the length of the second soldering material 6 extending from the second soldering outlet 43 is 0.2cm-2cm, which can be 0.2cm, 0.4cm, 1cm or 1.5cm, and can also be other values within the above range, which is not limited here. It can be understood that the length of the second soldering material 6 extending from the second soldering outlet 43 is within the above range, which is beneficial to control the welding area of the second soldering part 31, thereby being beneficial to improve the welding strength between the tab 2 and the composite current collector 1 and reduce the contact resistance between the tab 2 and the composite current collector 1.

[0083] In some embodiments, the thickness of the first soldering material and the second soldering material is ≤1mm, which can be 1mm, 0.9mm, 0.8mm, 0.6mm, 0.5mm or 0.3mm, and can also be other values within the above range, which is not limited here.

[0084] It should be noted that the thicknesses of the first soldering part and the second soldering part are related to the extension lengths of the first soldering material and the second soldering material and the thicknesses of the first soldering material and the second soldering material. In the case where the thicknesses of the first soldering material and the second soldering material are the same, although the extension length of the first soldering material is greater than the length of the second soldering material, the first soldering material flows along the horizontal direction of the composite current collector during the soldering melting process, while the second soldering material flows along the thickness direction of the current collector during the soldering melting process, thus finally resulting in that the thickness of the second soldering part is greater than the thickness of the first soldering part.

[0085] In some embodiments, the first soldering material and the second soldering material include at least one of a tin wire, a tin sheet, a soldering paste, a tin-lead alloy wire, a tin-lead alloy sheet, a tin-copper alloy wire, a tin-copper alloy sheet, and a flux. In actual applications, the first soldering material and the second soldering material can use the same material or different materials, which are not limited herein. Preferably, a tin sheet or a tin wire is selected as the soldering material, and a soldering paste and a flux are applied on the surface of the tin sheet or the tin wire.

[0086] In step S200, the composite current collector 1 is arranged on the workbench 41 of the tab soldering device, and the tab soldering area of the composite current collector 1 is located between the first soldering material 5 and the second soldering material 6 in the height direction.

[0087] In some embodiments, the second soldering material 6 is laid on the workbench 41, and the first soldering material 5 extending from the first soldering material outlet 42 is higher than the second soldering material 6 in the height direction.

[0088] In some embodiments, the height difference between the first soldering material 5 and the second soldering material 6 is 2mm-10mm, and can be 2mm, 3mm, 5mm, 6mm, 8mm or 10mm, and can also be other values within the above range, which are not limited herein. It can be understood that the height difference between the first soldering material and the second soldering material within the above range is beneficial to realize the soldering between the tab and the composite current collector.

[0089] In some embodiments, the composite current collector 1 includes a first metal layer 11, a polymer macromolecular layer 10 and a second metal layer 12 arranged in layers, and the surface of the first metal layer 11 is provided with a tab soldering area.

[0090] In some embodiments, the first metal layer 11 and the second metal layer 12 include a copper layer and / or an aluminum layer.

[0091] In some embodiments, the first metal layer 11 has a thickness of 0.5-2 μm, specifically 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm or 2 μm, or other values within the above range.

[0092] In some embodiments, the second metal layer 12 has a thickness of 0.5-2 μm, specifically 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.6 μm, 1.8 μm or 2 μm, or other values within the above range.

[0093] In some embodiments, the polymer macromolecular layer 10 comprises at least one of a polyethylene terephthalate film layer (PET film layer), a polypropylene film layer (PP film layer) and a polyimide film layer (PI film layer).

[0094] In some embodiments, the polymer macromolecular layer 10 has a thickness of 1-10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or other values within the above range.

[0095] In step S300, the tab 2 is placed above the first solder material 5, and a portion of the tab 2 overlaps the composite current collector 1.

[0096] In some embodiments, the tab 2 comprises at least one of metal copper, metal aluminum, metal nickel, copper-aluminum alloy, copper-nickel alloy, aluminum-nickel alloy or copper-aluminum-nickel alloy.

[0097] In some embodiments, the tab 2 has a thickness of ≤1 mm, specifically 1 mm, 0.9 mm, 0.8 mm, 0.6 mm, 0.5 mm or 0.3 mm, or other values within the above range. It can be understood that the thickness of the tab 2 within the above range can reduce the resistance and improve the current transmission efficiency, can provide sufficient strength to ensure that the tab 2 is not easily deformed or broken during welding and use, and can also ensure the welding quality, which is conducive to improving the welding strength between the tab 2 and the composite current collector 1.

[0098] In some embodiments, the length of the overlapping part of the tab 2 and the composite current collector 1 is 1-5 cm, and can be 1 cm, 1.5 cm, 2 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm or 5 cm, or other values within the above range. It can be understood that the length of the overlapping part of the tab 2 and the composite current collector 1 within the above range can ensure that there is sufficient contact area between the tab 2 and the conductive welding part 3, thereby improving the welding strength between the tab 2 and the composite current collector 1, reducing the contact resistance between the tab 2 and the composite current collector 1, and ensuring smooth transmission of current through the conductive welding part 3, thereby facilitating the conduction of the first metal layer 11 and the second metal layer 12 on both sides of the polymer layer 10 in the composite current collector 1.

[0099] In step S400, the temperature of the welding head of the tab welding device is raised to a preset temperature, and the pressing device of the tab welding device is adjusted to drive the welding head to press down and maintain a preset pressing force.

[0100] The present application adjusts the temperature of the welding head and the pressing force to melt and solidify the first solder material and the second solder material to connect the composite current collector and the tab, which is simple and efficient, can ensure the welding strength, reduce the resistance, and reduce the welding defects and increase the welding consistency.

[0101] In some embodiments, the preset temperature of the welding head is 150-250°C, and can be 150°C, 160°C, 180°C, 200°C, 220°C or 250°C, or other values within the above range. It can be understood that the temperature of the welding head within the above range can make the first solder material and the second solder material melt and flow, which is conducive to the welding of the composite current collector and the tab.

[0102] In some embodiments, the pressing force P satisfies 0

[0103] In some embodiments, the pressing device satisfies 0 < T ≤ 5s in the holding time T after pressing, and specifically can be 0.5s, 1s, 1.5s, 2s, 3s, 4s or 5s, and of course can also be other values in the above range, which is not limited herein.

[0104] In a third aspect, the application provides a battery, which comprises the tab structure of the composite current collector of the first aspect or the tab structure of the composite current collector welded by the welding method of the second aspect.

[0105] In a fourth aspect, the application provides a welding device 4 for preparing the tab structure of the composite current collector of the first aspect, as shown in the welding device diagram of the tab structure of the composite current collector, the welding device comprises: Figure 5

[0106] A base 40, the upper surface of the base 40 is provided with a workbench 41, and a first solder outlet 42 and a second solder outlet 43 are respectively arranged on the opposite sides of the workbench 41, and the first solder outlet 42 and the second solder outlet 43 are adjustable in the horizontal direction and the height direction.

[0107] A liftable pressing device 44 connected with a welding head 45, the pressing device 44 drives the welding head 45 to press down, and the pressing pressure and the holding time of the welding head 45.

[0108] In some embodiments, the pressing device 44 is provided with a temperature adjusting device of the welding head 45.

[0109] The welding device of the tab structure of the composite current collector has simple structure and can realize automatic production, and can be safely used in the preparation of the battery cell.

[0110] In some embodiments, the pressing device 44 comprises a lifting assembly 441 and a support 442, the lifting assembly 441 is connected with the base 40, the support 442 is connected with the lifting assembly 441 and is arranged in the horizontal direction, and the end of the support 442 is connected with the welding head 45; the lifting assembly 441 drives the support 442 to move up and down in the height direction, and the position of the welding head 45 and the position of the first solder outlet 42 can be adjusted according to the thickness of the composite current collector 1, which is beneficial to improve the welding efficiency.

[0111] In some embodiments, the first solder outlet 42 is movably connected with the lifting assembly 441, and the first solder outlet 42 is arranged in parallel with the support 442, and when the welding head 45 moves in the height direction, the first solder outlet 42 does not interfere with the welding head 45 and does not affect the up and down movement of the welding head, which is beneficial to improve the welding efficiency.

[0112] Example 1 ​

[0113] (1) Prepare the composite current collector 1, which includes a copper layer 11 with a thickness of 1 μm, a PET film layer 10 with a thickness of 4 μm, and a copper layer 12 with a thickness of 1 μm, which are stacked, and the surface of the copper layer 11 is provided with a tab welding area;

[0114] (2) Turn on the power supply of the welding device 4 as shown in Figure 5 , so that it is in working condition; prepare a tin wire 5 with a thickness of 100 μm and a tin sheet 6 with a thickness of 100 μm, and place the tin wire 5 into the first solder outlet part 42 and adjust its length to 3 cm from the first solder outlet part 42, and place the tin sheet 6 into the second solder outlet part 43 and adjust its length to 0.5 cm from the second solder outlet part 43; Figure 5

[0115] (3) Adjust the positions of the first solder outlet part 42 and the second solder outlet part 43 so that the tin sheet 6 is laid on the workbench 41, adjust the height of the first solder outlet part 42, and fix it at a height of 0.5 cm higher than the second solder outlet part 43;

[0116] (4) Place the composite current collector 1 on the workbench 41 of the welding device 4, and the tab welding area of the composite current collector 1 is located between the tin wire 5 and the tin sheet 6 in the height direction, place the metal nickel tab 2 above the tin wire 5, and make a part of the metal nickel tab overlap the composite current collector 1 by 4 cm, as shown in Figure 6 , from top to bottom, the metal nickel tab 2, the tin wire 5, the composite current collector 1, and the tin sheet 6, adjust the position of the welding head 43 so that it is aligned with the metal nickel tab 2 below;

[0117] (5) Adjust the temperature of the welding head 43 to 180℃, adjust the pressing pressure of the pressing device 42 to 0.1 Mpa, set the holding time to 2 s, and after the temperature reaches 180℃, adjust the pressing device 44, which drives the welding head to press down and maintain for 2 s, control the separation of the pressing device 44 and the composite current collector 1, and obtain the composite current collector after welding the tab.

[0118] ​The tab structure of the composite current collector obtained in this embodiment includes: a composite current collector 1, which includes a copper layer 11, a PET film layer 10, and a copper layer 12 stacked together, with a tab welding area on the surface of the copper layer 11; a nickel tab 2, which is connected to the tab welding area by a conductive welding part 3, which includes a first solder part 31 and a second solder part 32; the surface of the first metal layer 11 is connected to the nickel tab 2 by the first solder part 31; at least a portion of the second solder part 32 covers the copper layer 12 of the composite current collector 1, and at least a portion of the second solder part 32 extends from the copper layer 12 of the composite current collector 1 to the copper layer 11 in the thickness direction of the composite current collector 1, so that the composite current collector 1 and the nickel tab 2 are connected by the second solder part 32.

[0119] The thickness of the first solder portion 31 is 50 μm, the thickness of the second solder portion 32 is 100 μm, the distance between the first solder portion 31 and the second solder portion 32 is 10 mm, the length of the second solder portion 32 covering the copper layer 12 of the composite current collector 1 is 2 mm, and the length of the second solder portion 32 extending to the copper layer 11 is 3 mm.

[0120] Figure 7 This is a schematic diagram of the front (top) structure of the composite current collector's tab structure after welding, as shown in Embodiment 1 of this application; Figure 7 As shown, the first solder portion 31 is hidden between the copper layer 11 and the nickel tab 2 of the composite current collector 1.

[0121] Figure 8 This is a schematic diagram of the reverse (bottom) structure of the composite current collector's tab structure after welding, as shown in Embodiment 1 of this application. Figure 8 As shown, the second solder section 32 is partially exposed to the outside, connecting the copper layer 12 of the nickel tab 2 and the composite current collector 1.

[0122] Figure 9 A resistance test location diagram of the tab structure of the composite current collector provided in the embodiments of this application is shown below. Figure 9 As shown, respectively for Figure 9 Resistance tests are performed at resistance test positions 1 and 2 as shown. The maximum resistance obtained from the two tests is the typical resistance value of the overall weld.

[0123] In this embodiment, the welding pull force of the nickel tab and the composite current collector is >10N / 6mm, and the typical resistance of the overall weld is 6.4mΩ.

[0124] Example 2

[0125] (1) Prepare the composite current collector 1, which includes an aluminum layer 11 with a thickness of 1 μm, a PET film layer 10 with a thickness of 4 μm, and an aluminum layer 12 with a thickness of 1 μm arranged in a stack, and the surface of the aluminum layer 11 is provided with a tab welding area;

[0126] (2) Turn on the power supply of the welding device 4 as shown in Figure 5 , so that it is in working condition; prepare a tin-lead alloy wire 5 with a thickness of 100 μm and a tin-lead alloy sheet 6 with a thickness of 100 μm, and place the tin-lead alloy wire 5 into the first solder discharge part 42 and adjust its length so that it protrudes 3 cm from the first solder discharge part 42, and place the tin-lead alloy sheet 6 into the second solder discharge part 43 and adjust its length so that it protrudes 0.5 cm from the second solder discharge part 43, and apply flux on the tin-lead alloy wire 5 and the tin-lead alloy sheet 6; Figure 5

[0127] (3) Adjust the positions of the first solder discharge part 42 and the second solder discharge part 43 so that the tin-lead alloy sheet 6 is laid flat on the workbench 41, adjust the height of the first solder discharge part 42, and fix the first solder discharge part 42 at a height of 0.5 cm higher than the second solder discharge part 45;

[0128] (4) Place the composite current collector 1 on the workbench 41 of the welding device 4, and the tab welding area of the composite current collector 1 is located between the tin-lead alloy wire 5 and the tin-lead alloy sheet 6 in the height direction, and place the metal aluminum tab 2 above the tin-lead alloy wire 5, and make a part of the metal aluminum tab overlap the composite current collector 1 by 4 cm, as shown in Figure 6 , from top to bottom, the metal aluminum tab 2, the tin-lead alloy wire 5, the composite current collector 1, and the tin-lead alloy sheet 6, and adjust the position of the welding head 43 so that it is aligned with the metal aluminum tab 2 below;

[0129] (5) Adjust the temperature of the welding head 43 to 180°C, adjust the pressing pressure of the pressing device 42 to 0.2 Mpa, set the holding time to 2 s, and after the temperature reaches 180°C, adjust the pressing device 44, which drives the welding head to press down and maintain for 2 s, control the separation of the pressing device 44 from the composite current collector 1, and obtain the composite current collector after welding the tab.

[0130] ​The tab structure of the composite current collector obtained in this embodiment includes: a composite current collector 1, which includes an aluminum layer 11, a PET film layer 10, and an aluminum layer 12 stacked together, with a tab welding area on the surface of the aluminum layer 11; a metal aluminum tab 2, which is connected to the tab welding area by a conductive welding part 3, which includes a first solder part 31 and a second solder part 32; the surface of the aluminum layer 11 and the metal aluminum tab 2 are connected by the first solder part 31; at least a portion of the second solder part 32 covers the aluminum layer 12 of the composite current collector 1, and at least a portion of the second solder part 32 extends from the aluminum layer 12 of the composite current collector 1 to the aluminum layer 11 in the thickness direction of the composite current collector 1, so that the composite current collector 1 and the metal aluminum tab 2 are connected by the second solder part 32.

[0131] The thickness of the first solder part 31 is 30μm, the thickness of the second solder part 32 is 50μm, the distance between the first solder part 31 and the second solder part 32 is 10mm, the length of the second solder part 32 covering the aluminum layer 12 of the composite current collector 1 is 2mm, and the length of the second solder part 32 extending to the aluminum layer 11 is 3mm.

[0132] In this embodiment, the welding pull force of the aluminum tab and the composite current collector is >5N / 5mm, and the typical resistance of the overall welded part is 13.3mΩ.

[0133] Example 3

[0134] The difference from Example 1 is:

[0135] (2) Figure 5 The power supply to the welding device 4 shown is turned on, putting it into working condition; prepare 100μm thick solder wire 5 and 100μm thick solder sheet 6, as follows. Figure 5 As shown, solder wire 5 is placed into the first solder feeding section 42 and its length is adjusted so that it extends 4cm from the first solder feeding section 42; solder sheet 6 is placed into the second solder feeding section 43 and its length is adjusted so that it extends 0.5cm from the second solder feeding section 43.

[0136] Figure 2 This is a schematic diagram of the tab structure of the composite current collector provided in Embodiment 3 of this application, as shown below. Figure 2As shown, the tab structure of the composite current collector obtained in this embodiment includes: a composite current collector 1, which includes a copper layer 11, a PET film layer 10, and a copper layer 12 stacked together, with a tab welding area on the surface of the copper layer 11; a nickel tab 2, which is connected to the tab welding area by a conductive welding part 3, which includes a first solder part 31 and a second solder part 32; the surface of the copper layer 11 is connected to the nickel tab 2 by the first solder part 31; at least a portion of the second solder part 32 covers the copper layer 12 of the composite current collector 1, and at least a portion of the second solder part 32 extends from the copper layer 12 of the composite current collector 1 to the copper layer 11 in the thickness direction of the composite current collector 1, so that the composite current collector 1 and the nickel tab 2 are connected by the second solder part 32.

[0137] The thickness of the first solder portion 31 is 50 μm, the thickness of the second solder portion 32 is 100 μm, the distance between the first solder portion 31 and the second solder portion 32 is 0 mm, the length of the second solder portion 32 covering the copper layer 12 of the composite current collector 1 is 2 mm, and the length of the second solder portion 32 extending to the copper layer 11 is 3 mm.

[0138] In this embodiment, the welding pull force of the nickel tab 2 and the composite current collector 1 is >10N / 6mm, and the typical resistance of the overall weld is 5.8mΩ.

[0139] Example 4

[0140] Unlike Example 1:

[0141] (2) Figure 5 The power supply to the welding device 4 shown is turned on, putting it into working condition; prepare 100μm thick solder wire 5 and 100μm thick solder sheet 6, as follows. Figure 5 As shown, solder wire 5 is placed into the first solder feeding section 42 and its length is adjusted so that it extends 4cm from the first solder feeding section 42; solder sheet 6 is placed into the second solder feeding section 43 and its length is adjusted so that it extends 1cm from the second solder feeding section 43.

[0142] Figure 3 This is a schematic diagram of the tab structure of the composite current collector provided in Embodiment 4 of this application, as shown below. Figure 3As shown, the tab structure of the composite current collector obtained in this embodiment includes: a composite current collector 1, which includes a copper layer 11, a PET film layer 10, and a copper layer 12 stacked together, with a tab welding area on the surface of the copper layer 11; a nickel tab 2, which is connected to the tab welding area by a conductive welding part 3, which includes a first solder part 31 and a second solder part 32; the surface of the copper layer 11 is connected to the nickel tab 2 by the first solder part 31; at least a portion of the second solder part 32 covers the copper layer 12 of the composite current collector 1, and at least a portion of the second solder part 32 extends from the copper layer 12 of the composite current collector 1 to the copper layer 11 in the thickness direction of the composite current collector 1, so that the composite current collector 1 and the nickel tab 2 are connected by the second solder part 32.

[0143] The thickness of the first solder portion 31 is 50 μm, the thickness of the second solder portion 32 is 100 μm, the distance between the first solder portion 31 and the second solder portion 32 is 0 mm, the length of the second solder portion 32 covering the copper layer 12 of the composite current collector 1 is 2 mm, and the length of the second solder portion 32 extending to the copper layer 11 is 8 mm.

[0144] In this embodiment, the welding pull force of the nickel tab 2 and the composite current collector 1 is >10N / 6mm, and the typical resistance of the overall weld is 5.1mΩ.

[0145] Example 5

[0146] The difference from Example 1 is:

[0147] (2) Figure 5 The power supply to the welding device 4 shown is turned on, putting it into working condition; prepare 100μm thick solder wire 5 and 100μm thick solder sheet 6, as follows. Figure 5 As shown, solder wire 5 is placed into the first solder feeding section 42 and its length is adjusted so that it extends 3cm from the first solder feeding section 42; solder sheet 6 is placed into the second solder feeding section 43 and its length is adjusted so that it extends 1cm from the second solder feeding section 43.

[0148] Figure 4 This is a schematic diagram of the tab structure of the composite current collector provided in Embodiment 4 of this application, as shown below. Figure 4As shown, the tab structure of the composite current collector obtained in the embodiment includes: a composite current collector 1, the composite current collector 1 includes a copper layer 11, a PET film layer 10 and a copper layer 12 which are stacked, the surface of the copper layer 11 is provided with a tab welding area; a metal nickel tab 2, the metal nickel tab 2 is connected with the tab welding area through a conductive welding part 3, the conductive welding part 3 includes a first solder part 31 and a second solder part 32; the surface of the copper layer 11 is connected with the metal nickel tab 2 through the first solder part 31; at least part of the second solder part 32 covers the copper layer 12 of the composite current collector 1, and at least part of the second solder part 32 extends from the copper layer 12 of the composite current collector 1 to the copper layer 11 in the thickness direction of the composite current collector 1, so that the composite current collector 1 is connected with the metal nickel tab 2 through the second solder part 32.

[0149] The thickness of the first solder part 31 is 50 μm, the thickness of the second solder part 32 is 100 μm, the distance between the first solder part 31 and the second solder part 32 is 13 mm, the length of the second solder part 32 covering the copper layer 12 of the composite current collector 1 is 2 mm, and the length of the second solder part 32 extending to the copper layer 11 is 8 mm.

[0150] In the embodiment, the welding straight pull force of the metal nickel tab 2 and the composite current collector 1 is greater than 10 N / 6 mm, and the typical resistance value of the overall welding position is 5.7 mΩ.

[0151] The above only is the preferred embodiment of the present application, and does not limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A tab structure for a composite current collector, characterized in that, include: A composite current collector, comprising a first metal layer, a polymer layer, and a second metal layer stacked together, wherein the surface of the first metal layer is provided with a tab welding area; The electrode tab is connected to the electrode tab welding area via a conductive welding part, the conductive welding part including a first solder part and a second solder part; The surface of the first metal layer is connected to the electrode tab via the first solder portion; At least a portion of the second solder portion covers the second metal layer of the composite current collector, and at least a portion of the second solder portion extends from the second metal layer of the composite current collector along the thickness direction of the composite current collector to the first metal layer, such that the composite current collector and the electrode are connected through the second solder portion, the second solder portion contacts the side surface of the composite current collector, and the second solder portion contacts the electrode; the thickness of the portion of the second solder portion along the thickness direction of the composite current collector is greater than the thickness of the first solder portion, the thickness of the first solder portion is 20μm to 40μm, and the thickness of the second solder portion is 50μm to 100μm.

2. The electrode structure of the composite current collector according to claim 1, characterized in that, The second solder portion extends from the second metal layer of the composite current collector along the thickness direction of the composite current collector to the first metal layer for a length of 0.1 mm to 10 mm.

3. The tab structure of the composite current collector according to claim 1, characterized in that, The length of the second metal layer covering the composite current collector in the second solder portion is 0.1 mm to 10 mm.

4. The tab structure of the composite current collector according to claim 1, characterized in that, When the second solder portion extends from the second metal layer of the composite current collector along the thickness direction of the composite current collector to the first metal layer, the distance between the first solder portion and the second solder portion is 0mm to 20mm.

5. The electrode structure of the composite current collector according to claim 1, characterized in that, The total length of the electrode tab is 3cm to 7cm, and the length of the overlap between the electrode tab and the composite current collector is 1cm to 5cm.

6. A welding method for the tab structure of a composite current collector as described in any one of claims 1 to 5, characterized in that, The method includes the following steps: Prepare a first solder material and a second solder material. The first solder material extends from the first solder discharge section of the electrode welding device, and the second solder material extends from the second solder discharge section of the electrode welding device. Adjust the height and horizontal direction of the first solder discharge section and / or the second solder discharge section so that the first solder discharge section and the second solder discharge section are on the same horizontal line. The composite current collector is placed on the worktable of the tab welding device, and the tab welding area of ​​the composite current collector is located between the first solder material and the second solder material along the height direction; The electrode tab is positioned above the first solder material, and a portion of the electrode tab overlaps with the composite current collector. The temperature of the welding head of the electrode welding device is raised to a preset temperature, and the pressing device of the electrode welding device is adjusted. The pressing device drives the welding head to press down and maintains the preset pressing pressure. The downward pressing device is controlled to rise and separate from the composite current collector, thus obtaining the composite current collector after welding the electrode tab.

7. The welding method for the electrode structure of the composite current collector according to claim 6, characterized in that, The length of the first solder material extending from the first solder discharge part is 1cm to 5cm; and / or, the length of the second solder material extending from the second solder discharge part is 0.2cm to 2cm.

8. The welding method for the tab structure of the composite current collector according to claim 6, characterized in that, The first solder material and the second solder material include at least one of tin wire, tin sheet, solder paste, tin-lead alloy wire, tin-lead alloy sheet, tin-copper alloy wire, copper alloy wire, and flux.

9. The welding method for the tab structure of the composite current collector according to claim 6, characterized in that, The length of the overlap between the electrode tab and the composite current collector is 1cm to 5cm.

10. The welding method for the tab structure of the composite current collector according to claim 6, characterized in that, The preset temperature of the welding head is 150℃~250℃.

11. The welding method for the electrode structure of the composite current collector according to claim 6, characterized in that, The pressing pressure P satisfies 0 < P ≤ 0.4 MPa, and the pressure holding time T after pressing satisfies 0 < T ≤ 5 s.

12. The welding method for the electrode structure of the composite current collector according to claim 6, characterized in that, The second solder material is laid flat on the workbench, and the first solder material extending from the first solder discharge part is higher than the second solder material in the height direction.

13. A battery, characterized in that, The battery includes a tab structure of a composite current collector as described in any one of claims 1 to 5, or a tab structure of a composite current collector obtained by welding according to the welding method of the tab structure of a composite current collector as described in any one of claims 6 to 12.

14. A welding apparatus for preparing the tab structure of the composite current collector as described in any one of claims 1 to 5, characterized in that, The welding apparatus includes: A base is provided, on which a workbench is mounted. On opposite sides of the workbench, a first solder feeding section and a second solder feeding section are respectively provided. The first solder feeding section and the second solder feeding section are adjustable in both the horizontal and vertical directions. A liftable pressing device is connected to a welding head. The pressing device drives the welding head to press down and adjusts the pressing pressure and holding time of the welding head.

15. The welding apparatus for the electrode structure of the composite current collector according to claim 14, characterized in that, The pressing device is equipped with a temperature regulating device for the welding head.

16. The welding apparatus for the electrode structure of the composite current collector according to claim 14, characterized in that, The pressing device includes a lifting assembly and a support member. The lifting assembly is connected to the base, and the support member is connected to the lifting assembly and extends horizontally. The end of the support member is connected to the welding head. The lifting assembly drives the support member to move up and down along the height direction.

17. The welding apparatus for the electrode structure of the composite current collector according to claim 16, characterized in that, The first solder feeding part is movably connected to the lifting assembly, and the first solder feeding part is arranged parallel to the support member. When the soldering head moves along the height direction, the first solder feeding part and the soldering head do not interfere with each other.

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