A welding method, welding structure, and battery for a composite current collector and tab

Abstract

This invention provides a welding method, welding structure, and battery for a composite current collector and an electrode tab. The welding method includes: winding N layers inward from the second welding area of ​​the composite current collector to form a composite current collector unit with a winding area, wherein multiple first contact surfaces are formed between the second welding areas, and a second contact surface is formed between the second welding areas and the first welding areas and the first current converging area; stacking multiple composite current collector units vertically and fixing the winding areas of the multiple composite current collector units together; welding a first adapter piece to the bottom of the bottom composite current collector unit and a second adapter piece to the top of the top composite current collector unit; and welding and fixing the first adapter piece and the second adapter piece to the electrode tab of the battery, respectively. In this embodiment of the invention, since the second contact surfaces are all second welding areas, and the second welding areas are welded between polymer materials, welding is easier and more robust than welding between metal layers.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a welding method, welding structure, and battery for a composite current collector and electrode tab. Background Technology

[0002] With the continuous improvement of battery cycle performance and energy density, battery safety has become increasingly important. A composite current collector, composed of a polymer film and a metal coating, has gradually attracted widespread attention. This composite current collector with a polymer-metal coating structure effectively improves material strength and enhances the battery's resistance to punctures, compression, and heavy impacts, significantly improving its safety. Furthermore, the lightweight nature of the polymer increases the battery's energy density. However, this composite current collector uses a polymer as a carrier with conductive metal layers coated on both sides. Because the polymer in the middle is an insulating layer, the metal coatings on both sides cannot conduct electricity. Traditional welding methods directly weld the tabs of the multi-layer composite current collector, but the weld strength is poor and the internal resistance is high.

[0003] Chinese invention patent application CN110936010A discloses a method for welding composite current collector tabs. This invention first uses metal tabs to clamp and pre-weld a composite current collector A to form a electrode B. Then, electrode B and electrode A are stacked alternately from bottom to top. Finally, the multi-layered metal tabs are welded to the corresponding positive or negative electrode tab of the lithium battery. Chinese invention patent application CN111900413A discloses a method for welding composite current collector tabs in lithium batteries. This invention first uses two metal tabs to clamp and pre-weld a composite current collector tab to a conventional tab, stacking them alternately. Finally, the conductivity is improved through multi-layered tab final welding. While the methods in these two patents can solve the problem of poor conductivity during the welding process of composite current collectors, in actual operation, the pre-welding effect between the metal sheet and the composite current collector is poor, resulting in high internal resistance and low strength.

[0004] To solve the above problems, in the patent with patent number CN116706448A, the end of the composite current collector is wound to form a three-layer structure, with two contact surfaces between each layer, namely the first contact surface and the second contact surface. The first contact surface and the second contact surface are the metal of the upper and lower layers of the composite current collector in contact with each other, and the upper and lower metal layers are welded together. However, the metal on the composite current collector is relatively thin, and the welding point is in a folded state, which is difficult to operate and the welding is extremely difficult. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a welding method, welding structure and battery for a composite current collector and a tab, so as to solve the technical problem in the prior art that the welding between the upper and lower metal layers is extremely difficult because the metal on the composite current collector is relatively thin and the winding area is in a folded state.

[0006] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a method for welding a composite current collector to an electrode tab. The composite current collector includes a polymer material layer, a first current converging region and a first welding region disposed on a first surface of the polymer material layer, and a second current converging region and a second welding region disposed on a second surface of the polymer material layer. The first welding region and the second welding region are located at the same end of the polymer material layer, and the width of the second welding region is greater than the width of the first welding region. The welding method includes:

[0007] The second welding area of ​​the composite current collector is wound inward N layers, and the contact surfaces between any two adjacent layers are welded together to form a composite current collector unit with a winding area. A first contact surface is formed between the second welding area and the first welding area, and between the second current converging area and the first current converging area. A plurality of second contact surfaces are formed between the second welding areas.

[0008] Multiple composite current collectors are stacked together, and the winding areas of the multiple composite current collectors are fixedly connected.

[0009] A first adapter piece is welded to the bottom of the composite current collector at the bottom end, and a second adapter piece is welded to the top of the composite current collector at the top end.

[0010] The battery tabs are welded and fixed to the battery cover plate using the first adapter piece and the second adapter piece.

[0011] In some possible implementations, the width of the second welding area is greater than N-1 times that of the first welding area, and less than or equal to N times the width of the first welding area.

[0012] In some possible implementations, ultrasonic welding is used to weld the first contact surfaces together;

[0013] The second contact surfaces are welded together using ultrasonic welding.

[0014] In some possible implementations, the fixed connection of the winding areas of the plurality of composite current collector units specifically includes:

[0015] Multiple composite current collector units can be connected together using connectors, or the winding areas of any two adjacent composite current collector units can be welded together.

[0016] In some possible implementations, after connecting the free ends of the first adapter piece and the second adapter piece, the battery tabs are welded and fixed to the battery cover plate.

[0017] In some possible embodiments, the polymer material layer is any one of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene terephthalate, poly(p-phenylene terephthalate), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalate), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate;

[0018] The thickness of the polymer material layer is 3 μm to 8 μm.

[0019] In some possible implementations, the first current converging region is provided with a first current converging layer, and a first adhesive layer is provided between the first current converging layer and the polymer material layer, wherein the width of the first adhesive layer is the same as the width of the first current converging layer.

[0020] The second current converging region is provided with a second current converging layer, and a second adhesive layer is provided between the second current converging layer and the polymer material layer, the width of the second adhesive layer being the same as the width of the second current converging layer.

[0021] In some possible implementations, the first current converging layer and the second current converging layer are made of copper, aluminum, copper alloy, aluminum alloy, nickel alloy or titanium alloy.

[0022] The first adhesive layer and the second adhesive layer are made of nickel-copper alloy, aluminum oxide, silicon nitride or nickel-chromium alloy;

[0023] The thickness of the first current-converging layer and the second current-converging layer is 100 nm to 3 μm.

[0024] Secondly, embodiments of the present invention provide a welding structure for a composite current collector and an electrode tab, wherein the welding structure is prepared using any of the methods described in the first aspect.

[0025] Thirdly, embodiments of the present invention provide a battery including a positive electrode and a negative electrode, wherein the positive electrode has a positive tab and the negative electrode has a negative tab, and at least one of the positive electrode and the negative electrode uses the composite current collector and the tab welding structure described in the third aspect.

[0026] The beneficial technical effects of the above technical solution are as follows:

[0027] This invention provides a method, structure, and battery for welding a composite current collector to a tab. The composite current collector includes a polymer material layer, a first current converging region and a first welding region disposed on a first surface of the polymer material layer, and a second current converging region and a second welding region disposed on a second surface of the polymer material layer. The first and second welding regions are located at the same end of the polymer material layer, and the width of the second welding region is greater than the width of the first welding region. The welding method includes: winding the second welding region of the composite current collector inwards N layers to form a composite current collector unit with a winding region, wherein multiple first contact surfaces are formed between the second welding regions, and second contact surfaces are formed between the second welding regions and the first welding regions, and between the second current converging region and the first current converging region; stacking multiple composite current collector units vertically and fixing the winding regions of the multiple composite current collector units together; welding a first adapter piece to the bottom of the bottom composite current collector unit and welding a second adapter piece to the top of the top composite current collector unit; and welding and fixing the first and second adapter pieces to the tabs of the battery. In this embodiment of the invention, since the second contact surfaces are all second welding areas, and the second welding areas are welds between polymer materials, they are easier to weld and stronger than welds between metal layers. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a welding method for a composite current collector and an electrode tab according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a composite current collector according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of a composite current collector unit according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of a stacked structure of multiple composite current collector units according to an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of another composite current collector according to an embodiment of the present invention.

[0034] Explanation of icon numbers:

[0035] 1. Polymer material layer; 11. First current converging region; 12. First welding region; 13. Second current converging region; 14. Second welding region; 2. First current converging layer; 3. Second current converging layer; 4. First adhesive layer; 5. Second adhesive layer;

[0036] A. First contact surface; A1. Current-connecting region; B. Second contact surface; C. Composite current collector unit; C1. First adapter piece; C2. Second adapter piece; D. Winding region. Detailed Implementation

[0037] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. In the accompanying drawings and the following description, at least some well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the invention; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0038] Example 1

[0039] Figure 1 This is a flowchart illustrating a welding method between a composite current collector and an electrode tab according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a composite current collector according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of a composite current collector unit according to an embodiment of the present invention. Figure 4 This is a schematic diagram of a stacked structure of multiple composite current collector units according to an embodiment of the present invention, as shown below. Figures 1 to 4 As shown, the welding method includes the following steps:

[0040] Step S11: The second welding area 14 of the composite current collector is wound inward N layers, and the contact surfaces between any two adjacent layers are welded together to form a composite current collector unit C with a winding area. A first contact surface A is formed between the second welding area 14 and the first welding area 12, and between the second current converging area 13 and the first current converging area 11. A plurality of second contact surfaces B are formed between the second welding areas 14.

[0041] Step S12: Stack multiple composite current collector units C on top of each other and fix the winding area D of the multiple composite current collector units C together.

[0042] Step S13: Weld the first adapter piece C1 to the bottom of the composite current collector unit C at the bottom end, and weld the second adapter piece C2 to the top of the composite current collector unit C at the top end.

[0043] In step S14, the battery tabs are welded and fixed to the battery cover plate using the first adapter C1 and the second adapter C2.

[0044] The composite current collector includes a polymer material layer 1, a first current converging region 11 and a first welding region 12 disposed on the first surface of the polymer material layer 1, a second current converging region 13 and a second welding region 14 disposed on the second surface of the polymer material layer 1, the first welding region 12 and the second welding region 14 being located at the same end of the polymer material layer 1, and the width of the second welding region 14 being greater than the width of the first welding region 12.

[0045] Specifically, after winding the second welding zone 14 of the composite current collector inwards N layers, the contact surfaces between any two adjacent layers are welded together to form a structure as shown in the figure. Figure 3 The current collector unit C shown in this embodiment has N = 3, meaning it has 3 layers: a first layer, a second layer, and a third layer. Multiple current collector units C are fabricated using the method in step S11, and then fixedly stacked together to form a structure as shown. Figure 4 The stacked structure shown has a first adapter piece C1 and a second adapter piece C2 welded to both sides for connection with the battery tabs. This welding method in this embodiment is not only easy to weld, but also increases the structural strength while reducing internal resistance, avoiding the degradation of battery performance caused by poor welding or insufficient welding strength.

[0046] In this embodiment of the composite current collector unit C, the contact surface between the first layer and the second layer is the first contact surface A. The first contact surface A includes the contact surface between the second welding area 14 and the first welding area 12, and the contact surface between the second current converging area 13 and the first current converging area 11. The contact surface between the second layer and the third layer is the second contact surface B. The second contact surface B consists entirely of the contact surfaces between the second welding areas 14. Since both the first welding area 12 and the second welding area 14 are made of polymer materials, the welding between the second contact surfaces B consists entirely of polymer materials. A portion of the first contact surface A consists of welding between polymer materials, and another portion consists of welding between the first current converging area 11 and the second current converging area 13. This portion is used to conduct the current between the first current converging area 11 and the second current converging area 13. This portion is called the current conduction area A1. In this embodiment, only the current conduction area A1 consists of welding between metal layers. The other folded portions consist of welding between polymer materials. Compared to welding between all metal layers, polymer materials are easier to weld and the welding is more robust.

[0047] In addition, in the prior art, the first contact surface A and the second contact surface B are the upper and lower metal layers of the composite current collector in contact with each other. However, the inventors found in the research process that in actual use, the upper and lower metal layers of the second contact surface B do not interact with the other parts of the metal in the first contact surface A except for the current conduction area. This results in the waste of this part of the metal, which increases the cost of manufacturing the current collector. At the same time, retaining this part of the metal will also increase the weight of the current collector, which will affect the energy density of the battery when it is used in the battery later.

[0048] In this embodiment, the composite current collector can be prepared by the following method:

[0049] A polymer material layer 1 is obtained; a mask is used to block both ends of the first surface of the polymer material layer 1, forming a first current converging region 11 and a first welding region 12 on the first surface of the polymer material layer 1; a first current converging layer 2 is formed in the first current converging region 11 by vacuum deposition; a mask is used to block both ends of the second surface of the polymer material layer 1, forming a second current converging region 13 and a second welding region 14 on the second surface of the polymer material layer 1; a second current converging layer 3 is formed in the second current converging region 13 by vacuum deposition; wherein the width of the second welding region 14 is greater than the width of the first welding region 12.

[0050] In some embodiments, the width of the second welding area 14 is greater than N-1 times the width of the first welding area 12, and less than or equal to N times the width of the first welding area 12. Here, N is the number of layers wound around the end of the current collector. In this embodiment, regardless of the number of layers wound around the composite current collector, a current-connecting area A1 is formed only on the first contact surface A. The length of the current-connecting area A1 can be 0 to 10 cm, which can be 1 / 3 to 2 / 3 of the winding area D. This is because a longer current-connecting area A1 makes welding more difficult, while a smaller area may cause heat generation when current flows through, reducing its current-carrying capacity.

[0051] In some embodiments, ultrasonic welding can be used to weld the first contact surface A together; ultrasonic welding can also be used to weld the second contact surface B together. The advantages of using ultrasonic welding in this embodiment include: ultrasonic welding enables a rapid welding process, improving production efficiency; compared to traditional hot-press welding or fusion welding, ultrasonic welding consumes less energy, which is beneficial for energy conservation and emission reduction; ultrasonic welding typically does not require external welding materials, reducing material costs and potential contaminants generated during the welding process; ultrasonic welding generates less heat, which can reduce the thermal impact on the battery current collector material, helping to maintain the performance stability of the battery material; ultrasonic welding can achieve high-quality welding, with high weld joint strength and a stable and reliable connection after welding; moreover, in this embodiment, because the weld joint is in a folded state, welding between plastics is more convenient than welding all metals, greatly reducing the welding difficulty.

[0052] In some embodiments, the winding areas D of multiple composite current collector units C are fixedly connected, specifically including: connecting the multiple composite current collector units C together using a connector, or welding the winding areas D of any two adjacent composite current collector units C together. The connector can be various forms of mechanical connecting elements, such as bolts, nuts, studs, pins, or shafts, used to fix the multiple composite current collector units together through threaded or pin connections. Furthermore, the connector can also be a specially designed clamping, snap-fit, or locking component for clamping and fixing the multiple composite current collector units. The connector can also be a conductive connector for achieving electrical connections between the multiple composite current collector units.

[0053] In some embodiments, to facilitate the connection between the battery tabs and the battery cover, the first adapter piece C1 and the second adapter piece C2 can be welded to their free ends, i.e., the ends away from the tabs (winding area D), and then the battery tabs are connected to the battery cover. In this embodiment, the number of composite current collector units C can be determined by comprehensively considering factors such as the type of tab to be welded, the number of turns of the composite current collector, and the thickness of the composite current collector itself. Generally speaking, the distance between the first adapter piece C1 and the second adapter piece C2 needs to be adapted to the thickness of the tab.

[0054] In some embodiments, the polymer material layer 1 is any one of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene terephthalate, poly(p-phenylene terephthalate), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalate), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate; the thickness of the polymer material layer 1 is 3µm to 8µm. In this embodiment, the thickness of the polymer material layer 1 can be 3-8µm, which can greatly reduce the mass of the current collector while still having sufficient tensile strength. Optionally, the polymer material layer 1 is preferably made of polypropylene because it is resistant to most acids and alkalis, which can greatly improve the lifespan of the current collector.

[0055] Figure 5 This is a schematic diagram of another composite current collector according to an embodiment of the present invention, as shown below. Figure 5 As shown, in some embodiments, the first current converging region 11 is provided with a first current converging layer 2, and a first adhesive layer 4 is provided between the first current converging layer 2 and the polymer material layer 1, the width of the first adhesive layer 4 being the same as the width of the first current converging layer 2; the second current converging region 13 is provided with a second current converging layer 3, and a second adhesive layer 5 is provided between the second current converging layer 3 and the polymer material layer 1, the width of the second adhesive layer 5 being the same as the width of the second current converging layer 3.

[0056] Specifically, the materials of the first current converging layer 2 and the second current converging layer 3 can be copper, aluminum, copper alloy, aluminum alloy, nickel alloy or titanium alloy; the materials of the first adhesive layer 4 and the second adhesive layer 5 can be nickel copper alloy, aluminum oxide, silicon nitride or nickel chromium alloy; the thickness of the first current converging layer 2 and the second current converging layer 3 can be from 100nm to 3um.

[0057] In this embodiment, by providing the first adhesive layer 4, the adhesion between the first current converging layer 2 and the polymer material layer 1 can be greatly increased. Similarly, by providing the second adhesive layer 5, the adhesion between the second current converging layer 3 and the polymer material layer 1 can be greatly increased. This ensures a stronger bond between the current converging layer and the polymer material layer, improving the overall structural stability and reliability of the battery. The first adhesive layer 4 and the second adhesive layer 5 ensure good contact between the current converging layer and the polymer material layer, effectively conducting current, reducing resistance, and improving the battery's electrical performance. The width of the adhesive layer is the same as the width of the current converging layer, ensuring sufficient contact area between them, thereby improving the bonding strength and conduction efficiency. Furthermore, maintaining the same width ensures a uniform contact area between the adhesive layer and the current converging layer, avoiding unstable bonding quality due to uneven contact area, thus improving the overall performance and reliability of the battery.

[0058] Example 2

[0059] This invention also provides a welding structure for a composite current collector and an electrode tab, which is prepared using any of the methods described in one embodiment.

[0060] The welding structure of this embodiment solves the technical problem of high welding difficulty in the prior art where the contact surfaces during the winding process are all metal layers. It is not only easy to weld, but also improves the strength of the weld.

[0061] Example 3

[0062] This invention also provides a battery comprising a positive electrode and a negative electrode. The positive electrode has a positive tab, and the negative electrode has a negative tab. At least one of the positive and negative electrode plates uses the composite current collector and the tab welding structure of Embodiment 2. In this invention, the composite current collector can be either a positive or negative composite current collector; both are collectively referred to as composite current collectors in this application. The positive composite current collector is used for welding to the positive tab, and the negative composite current collector is used for welding to the negative tab.

[0063] In this welded structure, both the second contact surface B and the first contact surface A, except for the current-conducting region A1, are made of polymer materials. Since the upper and lower metal layers of the second contact surface B are completely incompatible with the rest of the metal in the first contact surface A, this results in wasted metal. This increases the cost of manufacturing the current collector and also increases its weight, affecting the battery's energy density when used in a battery. Therefore, the welded structure described in this embodiment not only saves costs but also significantly improves the battery's energy density.

[0064] The battery in this embodiment can be applied to various products or devices that require battery power, including but not limited to: portable electronic devices such as mobile phones, tablets, laptops, digital cameras, portable audio devices, etc.; power tools such as electric screwdrivers, electric drills, electric lawnmowers, electric saws, etc.; electric vehicles such as electric bicycles, electric motorcycles, electric cars, etc.; energy storage devices such as solar energy storage systems, wind energy storage systems, home energy storage systems, etc.; medical devices such as portable medical devices, medical electronic devices, etc.; drones and aircraft such as portable drones, aircraft power supplies, etc.

[0065] In the description of the embodiments of the present invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention embodiment should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method of welding a composite current collector and tab, characterized by, The composite current collector includes a polymer material layer (1), a first current converging region (11) and a first welding region (12) disposed on the first surface of the polymer material layer (1), a second current converging region (13) and a second welding region (14) disposed on the second surface of the polymer material layer (1), the first welding region (12) and the second welding region (14) being located at the same end of the polymer material layer (1), and the width of the second welding region (14) being greater than the width of the first welding region (12); the welding method includes: The second welding area (14) of the composite current collector is wound inward N layers, and the contact surfaces between any two adjacent layers are welded together to form a composite current collector unit (C) with a winding area (D). A first contact surface (A) is formed between the second welding area (14) and the first welding area (12), and between the second current converging area (13) and the first current converging area (11). A plurality of second contact surfaces (B) are formed between the second welding areas (14). Multiple composite current collector units (C) are stacked together, and the winding areas (D) of the multiple composite current collector units (C) are fixedly connected. A first adapter piece (C1) is welded to the bottom of the composite current collector unit (C) at the bottom end, and a second adapter piece (C2) is welded to the top of the composite current collector unit (C) at the top end. The battery tabs are welded and fixed to the battery cover plate using the first adapter piece (C1) and the second adapter piece (C2).

2. The welding method for a composite current collector and an electrode tab according to claim 1, characterized in that, The width of the second welding area (14) is greater than N-1 times that of the first welding area (12), and less than or equal to N times the width of the first welding area (12).

3. The method of claim 1, wherein the welding is performed by ultrasonic welding. The first contact surfaces (A) are welded together using ultrasonic welding; and the second contact surfaces (B) are welded together using ultrasonic welding.

4. The method of claim 1, wherein the welding is performed by ultrasonic welding. The fixed connection of the winding areas (D) of the plurality of composite current collector units (C) specifically includes: Multiple composite current collector units (C) are connected together using connectors, or the winding areas (D) of any two adjacent composite current collector units (C) are welded together by welding.

5. The method of claim 1, wherein the welding is performed by ultrasonic welding. After connecting the free ends of the first adapter piece (C1) and the second adapter piece (C2), the battery tabs are welded and fixed to the battery cover plate.

6. The welding method for a composite current collector and an electrode tab according to claim 1, characterized in that, The polymer material layer (1) is any one of polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyethylene terephthalate, poly(p-phenylene terephthalate), acrylonitrile-butadiene-styrene copolymer, poly(p-phenylene terephthalate), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber and polycarbonate; The thickness of the polymer material layer (1) is 3 μm to 8 μm.

7. The welding method for a composite current collector and an electrode tab according to claim 1, characterized in that, The first current converging region (11) is provided with a first current converging layer (2), and a first adhesive layer (4) is provided between the first current converging layer (2) and the polymer material layer (1). The width of the first adhesive layer (4) is the same as the width of the first current converging layer (2). The second current converging region (13) is provided with a second current converging layer (3), and a second adhesive layer (5) is provided between the second current converging layer (3) and the polymer material layer (1). The width of the second adhesive layer (5) is the same as the width of the second current converging layer (3).

8. The welding method for a composite current collector and an electrode tab according to claim 7, characterized in that, The first current converging layer (2) and the second current converging layer (3) are made of copper, aluminum, copper alloy, aluminum alloy, nickel alloy or titanium alloy; The first adhesive layer (4) and the second adhesive layer (5) are made of nickel-copper alloy, aluminum oxide, silicon nitride or nickel-chromium alloy; The thickness of the first current-converging layer (2) and the second current-converging layer (3) is 100 nm to 3 μm.

9. A welding structure for a composite current collector and an electrode tab, characterized in that, The welded structure is prepared using the method described in any one of claims 1 to 8.

10. A battery comprising a positive electrode and a negative electrode, characterized in that, The positive electrode has a positive tab, the negative electrode has a negative tab, and at least one of the positive and negative electrodes uses the composite current collector and tab welding structure as described in claim 9.

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