Composite current collector tab connecting structure, preparation method, double-cell structure and secondary battery

Abstract

In order to overcome the problem that the intermediate polymer layer of the composite current collector affects the circuit connection of the metal layers on both sides in the prior art, the application provides a composite current collector tab connection structure, a preparation method, a double-cell structure and a secondary battery. The composite current collector tab connection structure comprises a plurality of first tabs and a plurality of second tabs. The first tabs and the second tabs are both composite layer structures. The composite layer structure comprises a first metal layer, a second metal layer and a polymer layer. The polymer layer is arranged between the first metal layer and the second metal layer. The end portions of the plurality of second tabs are folded and inserted one by one and at intervals between the plurality of first tabs. The composite current collector tab connection structure provided by the application realizes the electrical connection between the plurality of first tabs and the plurality of second tabs by folding and inserting the plurality of second tabs at intervals between the plurality of first tabs, and then connects the electrical connection channels of the composite layer structure.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery manufacturing technology, specifically relating to a composite current collector tab connection structure, preparation method, dual-cell structure, and secondary battery. Background Technology

[0002] Current collectors play a crucial role in carrying and collecting the current generated by the active materials in a battery, thus significantly impacting the capacity, rate capability, and cycle life of lithium-ion batteries. Reducing current collector thickness has become a major development trend to improve battery energy density. However, excessively thin current collectors not only increase costs but also easily lead to problems such as wrinkling and breakage during manufacturing processes. Therefore, metal current collectors cannot be infinitely thinned. New composite structure current collectors offer significant advantages in improving battery safety, energy density, and cycle life.

[0003] Composite current collectors are a novel type of composite foil with a "sandwich" structure. The middle layer is a polymer base film, with aluminum or copper plated on both sides, corresponding to the aluminum and copper foils of the positive and negative electrodes in lithium-ion batteries. Because the upper and lower metal layers of the composite current collector are not connected, currently, conductive sheets are needed to connect the upper and lower metal plating layers before soldering them to the electrode tabs. This connection method requires conductive sheets to be connected to the metal layers on each side, which not only increases the battery weight and reduces its energy density but also affects the reliability of the soldering. In severe cases, it can lead to weak soldering, perforation, and ultimately, compromised electrical performance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the issue that the intermediate polymer layer of the composite current collector affects the circuit connectivity of the metal layers located on both sides of the polymer layer in the prior art. The present invention provides a composite current collector tab connection structure, preparation method, dual-cell structure and secondary battery.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A composite current collector tab connection structure is provided, including multiple first tabs and multiple second tabs;

[0007] Both the first electrode and the second electrode are composite layer structures, which include a first metal layer, a second metal layer and a polymer layer, with the polymer layer disposed between the first metal layer and the second metal layer.

[0008] The first ends of a plurality of first electrodes are stacked, and the second ends of a plurality of first electrodes are spaced apart along the thickness direction of the first electrodes;

[0009] The first ends of the plurality of second tabs are stacked and located outside the first ends of the outermost first tabs; the ends of the second ends of the plurality of second tabs are folded and inserted one by one between the second ends of the plurality of first tabs, and / or stacked outside the second ends of the outermost first tabs;

[0010] The first metal layer and / or the second metal layer of the ends of the second ends of the second tabs are electrically connected with the first metal layer and / or the second metal layer of the ends of the first tabs opposite to them.

[0011] Optionally, the second tab comprises a flat portion, a bent portion and an extension portion, the plurality of flat portions are stacked and located outside the first tabs, the plurality of bent portions are connected one by one to the plurality of flat portions and the plurality of extension portions, the plurality of extension portions are inserted one by one between the plurality of first tabs and / or stacked outside the outermost first tabs, and the plurality of extension portions and the plurality of first tabs are alternately stacked.

[0012] Optionally, the flat portion, the first tab and the extension portion are arranged in parallel.

[0013] Optionally, the composite current collector tab connection structure comprises a first fixed connection area and a second fixed connection area, in the first fixed connection area, the plurality of extension portions, the plurality of first tabs and the plurality of flat portions are fixedly connected in stack; in the second fixed connection area, the plurality of first tabs and the plurality of flat portions are fixedly connected in stack.

[0014] Optionally, the fixed connection is achieved by welding.

[0015] Optionally, the preparation method of the double-electricity-core structure comprises the following operation steps:

[0016] The ends of the plurality of first tabs and the ends of the plurality of second tabs are alternately stacked, and fixedly connected at the alternately stacked position to form the first fixed connection area;

[0017] The plurality of second tabs are folded outside the first fixed connection area, so that the main bodies of the plurality of second tabs and the main bodies of the plurality of first tabs are stacked with each other, and fixedly connected at the mutually stacked position to fixedly connect the plurality of first tabs and the plurality of second tabs into one body.

[0018] Optionally, it further comprises a third tab for external connection; the third tab is fixedly connected to the second tab located at the outermost side.

[0019] Optionally, the third tab is a hard tab welded to the outermost second tab.

[0020] Optionally, the first metal layer and the second metal layer of the first tab are copper foils or aluminum foils.

[0021] The first metal layer and the second metal layer of the second tab are copper foils or aluminum foils.

[0022] In another aspect, the application provides a dual-cell structure, comprising a first cell and a second cell, the first cell comprising a plurality of first positive tabs and a plurality of first negative tabs, the second cell comprising a plurality of second positive tabs and a plurality of second negative tabs, the first cell and the second cell being stacked.

[0023] The plurality of first positive tabs and the plurality of second positive tabs adopt the composite current collector tab connection structure, and the plurality of first negative tabs and the plurality of second negative tabs are connected; and / or,

[0024] The plurality of first positive tabs and the plurality of second positive tabs are connected, and the plurality of first negative tabs and the plurality of second negative tabs adopt the composite current collector tab connection structure; and / or,

[0025] The plurality of first positive tabs and the plurality of second positive tabs adopt the composite current collector tab connection structure, and the plurality of first negative tabs and the plurality of second negative tabs adopt the composite current collector tab connection structure.

[0026] Optionally, the first cell and the second cell are laminated cells.

[0027] Optionally, the first cell comprises a plurality of first positive plates, a plurality of first negative plates, and a first separator interposed between any adjacent first positive plate and first negative plate, the first positive tab being led out from one end or one side of the first positive plate, and the first negative tab being correspondingly led out from one end or one side of the first negative plate; and / or,

[0028] The second cell comprises a plurality of second positive plates, a plurality of second negative plates, and a second separator interposed between any adjacent second positive plate and second negative plate, the second positive tab being led out from one end or one side of the second positive plate, and the second negative tab being correspondingly led out from one end of the second negative plate.

[0029] Optionally, the first positive plate comprises a first positive current collector, the first negative plate comprises a first negative current collector, the second positive plate comprises a second positive current collector, and the second negative plate comprises a second negative current collector, the first positive current collector, the first negative current collector, the second positive current collector, and the second negative current collector are all composite layer structures, the first positive tab and the first positive current collector are an integral structure, the first negative tab and the first negative current collector are an integral structure, the second positive tab and the second positive current collector are an integral structure, and the second negative tab and the second negative current collector are an integral structure.

[0030] In another aspect, the application provides a secondary battery comprising the double-cell structure, wherein the double-cell structure comprises the composite current collector tab connection structure.

[0031] The application has the following beneficial effects:

[0032] In the double-cell structure provided by the application, the first ends of the plurality of first tabs are arranged in a stack, the first ends of the plurality of first tabs are arranged in a space, the first ends of the plurality of second tabs are arranged in a stack outside the first ends of the outermost first tabs, the end portions of the second ends of the plurality of second tabs are folded and inserted one by one in a space between the plurality of first tabs and / or arranged in a stack outside the outermost first tabs. In the application, the plurality of second tabs are folded and inserted in a space between the plurality of first tabs and / or arranged in a stack outside the outermost first tabs, which realizes the electrical connection between the plurality of first tabs and the plurality of second tabs, and further realizes the electrical connection path of the first metal layer, the second metal layer, and the polymer layer. Compared with the prior art, the application realizes the electrical connection of the current in the composite current collector by changing the connection structure of the plurality of first tabs and the plurality of second tabs without increasing additional conductive sheets. In addition, the application avoids increasing new conductive sheets, which is conducive to reducing the overall weight of the battery and further improving the energy density of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a schematic diagram of the composite current collector tab connection structure provided by the application;

[0034] Figure 2 is a schematic diagram of the composite current collector structure provided by the application;

[0035] Figure 3 is an exploded view of the double-cell structure provided by the application;

[0036] Figure 4 is Figure 3 is an enlarged view of C in the middle;

[0037] Figure 5 is a schematic diagram of the stack welding of the first tab and the second tab provided by the application;

[0038] Figure 6 is a first and second tab layer non-laminated position bending schematic diagram provided by the present application;

[0039] Figure 7 is a double cell structure and third tab welding structure schematic diagram provided by the present application.

[0040] The reference signs in the drawings of the specification are as follows:

[0041] 1, first cell; 11, first positive tab; 12, first negative tab; 2, second cell; 21, second positive tab; 22, second negative tab; 3, composite layer structure; 31, first metal layer; 32, second metal layer; 33, polymer layer; 4, first tab; 5, second tab; 51, flat part; 52, bending part; 53, extension; A, first fixed connection area; B, second fixed connection area; 6, third tab. DETAILED DESCRIPTION

[0042] In order to make the technical problems solved by the present application, the technical solutions and beneficial effects more clearly and clearly, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0043] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "radial", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0044] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] Reference Figure 1 , the embodiment of the present application provides a double cell structure, comprising a plurality of first tabs 4 and a plurality of second tabs 5;

[0046] The first tab 4 and the second tab 5 are both composite layer structures 3, which include a first metal layer 31, a second metal layer 32, and a polymer layer 33, the polymer layer 33 being disposed between the first metal layer 31 and the second metal layer 32 Figure 2

[0047] The first ends of the plurality of first tabs 4 are arranged in a stack, and the second ends of the plurality of first tabs 4 are arranged in a stack along the thickness direction of the first tab;

[0048] The first ends of the plurality of second tabs 5 are arranged in a stack outside the first ends of the outermost first tabs 4, and the second ends of the plurality of second tabs 5 are folded and inserted one by one between the second ends of the plurality of first tabs 4 and / or arranged in a stack outside the second ends of the outermost first tabs 4;

[0049] The first metal layer 31 and / or the second metal layer 32 of the end of the second end of the second tab 5 are electrically connected to the first metal layer 31 and / or the second metal layer 32 of the end of the second end of the first tab 4 opposite to it.

[0050] In the present application, the plurality of second tabs 5 are inserted one by one between the plurality of first tabs 4 and / or arranged in a stack outside the outermost first tabs 4 by folding, to realize the electrical connection between the plurality of first tabs 4 and the plurality of second tabs 5, and further realize the electrical connection path of the first metal layer 31, the second metal layer 32, and the polymer layer 33. Compared with the prior art, the present application realizes the electrical connection of the current in the composite current collector by changing the connection structure of the plurality of first tabs 4 and the plurality of second tabs 5 without additionally increasing the conductive sheet, and further avoids increasing the new conductive sheet, which is beneficial to reducing the overall weight of the battery and further improving the energy density of the battery.

[0051] In an embodiment, the second tab 5 includes a flat portion 51, a bent portion 52, and an extension portion 53, the plurality of flat portions 51 are arranged in a stack and located outside the first tab 4, the plurality of bent portions 52 are connected one by one to the plurality of flat portions 51 and the plurality of extension portions 53, the plurality of extension portions 53 are inserted one by one between the plurality of first tabs 4 and / or arranged in a stack outside the outermost first tabs 4, and the plurality of extension portions 53 and the plurality of first tabs 4 are arranged in a staggered stack.

[0052] Referring to Figure 1 ​Specifically, the bending part 52 is arranged to facilitate the electrical connection between the second tab 5 and the first tab 4. In addition, the plurality of extension parts 53 are inserted one by one between the plurality of first tabs 4, and the plurality of extension parts 53 and the plurality of first tabs 4 are alternately stacked. At this time, the plurality of extension parts 53 are stacked and covered on the first tab 4, which is beneficial to further increase the contact area when the second tab 5 is connected to the first tab 4, and can improve the reliability of the tab in the subsequent bending and welding process, and avoid problems such as virtual welding.

[0053] In an embodiment, the flat part 51, the first tab 4 and the extension part 53 are arranged in parallel.

[0054] In an embodiment, the composite current collector tab connection structure includes a first fixed connection area A and a second fixed connection area B. In the first fixed connection area A, the plurality of extension parts 53, the plurality of first tabs 4 and the plurality of flat parts 51 are stacked and fixedly connected. In the second fixed connection area B, the plurality of first tabs 4 and the plurality of flat parts 51 are fixedly connected.

[0055] The first fixed connection area A further includes a first area and a second area. In the first area, the plurality of extension parts 53 and the plurality of first tabs 4 are alternately stacked. In the second area, the plurality of flat parts 51 are stacked with each other.

[0056] In an embodiment, the fixed connection is achieved by welding.

[0057] Another embodiment of the present application provides a preparation method of a double-electricity-core structure, including the following operation steps:

[0058] The end portions of the plurality of first tabs 4 and the end portions of the plurality of second tabs 5 are alternately stacked, and are fixedly connected at the stacking position to form the first fixed connection area A.

[0059] The plurality of second tabs 5 are folded outside the first fixed connection area A, so that the main bodies of the plurality of second tabs 5 and the main bodies of the plurality of first tabs 4 are stacked in parallel with each other. The main bodies of the plurality of first tabs 4 and the main bodies of the plurality of second tabs 5 are fixedly connected to form an integrated structure.

[0060] Reference Figures 5-6 Specifically, the end portions of the plurality of first tabs 4 and the end portions of the plurality of second tabs 5 are alternately stacked, and are first welded at the stacking position. This operation can achieve the electrical connection between the first tab 4 and the second tab 5.

[0061] The main body of the plurality of second tabs 5 is folded outside the first fixed connection area A of the plurality of second tabs 5, and is stacked in parallel with the plurality of first tabs 4, and then second welding is performed at the stacking position, so that the first tab 4 and the plurality of second tabs 5 are welded together, thereby reducing the connection impedance and improving the welding reliability.

[0062] Referring to Figure 7 In an embodiment, a third tab 6 for external connection is further included; the third tab 6 is fixedly connected to the outermost second tab 5.

[0063] Specifically, the operation of welding the hard tab on the outermost second tab 5 can effectively improve the structural stability and conductivity of the secondary battery, thereby improving the service life and safety of the battery.

[0064] Specifically, the hard tab is generally made of a hard material, and the material of the hard tab in the present application can be a metal material such as aluminum or copper.

[0065] In an embodiment, the first metal layer 31 and the second metal layer 32 of the first tab 4 are copper foil or aluminum foil.

[0066] The first metal layer 31 and the second metal layer 32 of the second tab 5 are copper foil or aluminum foil.

[0067] Referring to Figures 3-4 Another embodiment of the present application provides a double-cell structure, which includes a first cell 1 and a second cell 2, the first cell 1 includes a plurality of first positive tabs 11 and a plurality of first negative tabs 12, the second cell 2 includes a plurality of second positive tabs 21 and a plurality of second negative tabs 22, and the first cell 1 and the second cell 2 are stacked.

[0068] The plurality of first negative tabs 12 and the plurality of second negative tabs 22 are connected; and / or, the plurality of first positive tabs 11 and the plurality of second positive tabs 21 are connected, the plurality of first negative tabs 12 and the plurality of second negative tabs 22 adopt the composite current collector tab connection structure; and / or, the plurality of first positive tabs 11 and the plurality of second positive tabs 21 adopt the composite current collector tab connection structure, and the plurality of first negative tabs 12 and the plurality of second negative tabs 22 adopt the composite current collector tab connection structure.

[0069] Specifically, among the plurality of first positive electrode tabs 11 and the plurality of first negative electrode tabs 12 on the first battery cell 1, the first positive electrode tabs 11 are used to lead out the current generated by the positive electrode of the battery cell, and the first negative electrode tabs 12 are used to conduct the negative electrode current; by connecting the plurality of first negative electrode tabs 12 and the plurality of second negative electrode tabs 22, the negative electrode current can be smoothly conducted between the two battery cells. Similarly, the plurality of first positive electrode tabs 11 and the plurality of second positive electrode tabs 21 can also be connected to realize the connection of the current paths of the two battery cells in the positive direction, ensuring that the current can flow orderly in the positive and negative loops.

[0070] The plurality of first negative electrode tabs 12 and the plurality of second negative electrode tabs 22 use a composite current collector tab connection structure to make the negative electrode current more efficient, stable, and reasonable in structure when conducted between the two battery cells. Similarly, the plurality of first positive electrode tabs 11 and the plurality of second positive electrode tabs 21 can also use a composite current collector tab connection structure to realize connection and further improve the positive electrode current conduction performance. In addition, the plurality of first positive electrode tabs 11 and the plurality of second positive electrode tabs 21, the plurality of first negative electrode tabs 12 and the plurality of second negative electrode tabs 22 all use the composite current collector tab connection structure to improve the electrical connection characteristics of the entire double battery cell structure, optimize the conduction effect of the current in the positive and negative loops to the greatest extent, and make the entire double battery cell structure achieve a more optimal state in terms of electrical performance.

[0071] Specifically, the first positive electrode tab 11 and the first negative electrode tab 12 are the first tab 4, the plurality of second positive electrode tabs 21 and the plurality of second negative electrode tabs 22 are the second tab 5, the plurality of first positive electrode tabs 11, the plurality of first negative electrode tabs 12, and the plurality of second positive electrode tabs 21, the plurality of second negative electrode tabs 22 are led out in the same direction, and then the end portions of the plurality of second positive electrode tabs 21 are folded and inserted one by one between the plurality of first positive electrode tabs 11, and the end portions of the plurality of second negative electrode tabs 22 are folded and inserted one by one between the plurality of first negative electrode tabs 12.

[0072] In an embodiment, the first battery cell 1 and the second battery cell 2 are laminated battery cells.

[0073] In the double battery cell structure, the first battery cell 1 and the second battery cell 2 adopt the form of laminated battery cells, and based on the good internal structural uniformity of the laminated battery cells, the current can flow more smoothly and stably between the battery cells and the tabs when connected, further improving the electrical performance and safety of the entire double battery cell structure.

[0074] In an embodiment, the first electrode 1 comprises a plurality of first positive electrode tabs, a plurality of first negative electrode tabs, and a first separator interposed between any adjacent first positive electrode tab and first negative electrode tab, the first positive electrode tab 11 is led out from one end or one side of the first positive electrode tab, and the first negative electrode tab 12 is correspondingly led out from one end or one side of the first negative electrode tab; and / or, the second electrode 2 comprises a plurality of second positive electrode tabs, a plurality of second negative electrode tabs, and a second separator interposed between any adjacent second positive electrode tab and second negative electrode tab, the second positive electrode tab 21 is led out from one end or one side of the second positive electrode tab, and the second negative electrode tab 22 is correspondingly led out from one end of the second negative electrode tab.

[0075] The first separator and the second separator can be a conventional separator, or a ceramic separator, a polymer separator, a non-woven fabric, an inorganic-organic composite separator, etc., including but not limited to a single-layer PP (polypropylene), a single-layer PE (polyethylene), a double-layer PP / PE, a double-layer PP / PP, and a triple-layer PP / PE / PP, etc.

[0076] In an embodiment, the first positive electrode tab comprises a first positive current collector, the first negative electrode tab comprises a first negative current collector, the second positive electrode tab comprises a second positive current collector, and the second negative electrode tab comprises a second negative current collector, the first positive current collector, the first negative current collector, the second positive current collector, and the second negative current collector are all composite layer structures 3, the first positive electrode tab 11 and the first positive current collector are an integral structure, the first negative electrode tab 12 and the first negative current collector are an integral structure, the second positive electrode tab 21 and the second positive current collector are an integral structure, and the second negative electrode tab 22 and the second negative current collector are an integral structure.

[0077] It should be noted that, in order to improve the energy density of the battery, a commonly used method is to reduce the thickness of the current collector, but a too-thin current collector cannot provide good mechanical strength and support, and therefore problems such as wrinkling and belt breaking are likely to occur in subsequent process procedures.

[0078] Specifically, the first positive current collector, the first negative current collector, the second positive current collector, and the second negative current collector described in the present application are all composite layer structures 3, i.e., the first metal layer 31 and the second metal layer 32 are combined with the polymer layer 33 as the metal conductive layer of the composite layer structure 3 to form a composite current collector with a multi-layer composite structure, which can provide better support and mechanical strength compared with a traditional current collector under the premise of meeting the requirement of collecting current.

[0079] The polymer layer 33 can be a PET film layer, a PP film layer or a PI film layer. Due to the use of high-molecular polymer materials in the polymer layer 33, the mass of the composite current collector formed is lighter than that of a traditional foil current collector with the same thickness, thereby facilitating the reduction of the overall weight of the assembled lithium ion battery. On the other hand, in the case where the volume of the battery cell remains unchanged, the lighter and thinner composite current collector can increase the filling amount of the active material, thereby improving the energy density of the battery.

[0080] The first metal layer 31 and the second metal layer 32 on both sides of the polymer layer 33 can be plated on both sides of the polymer layer 33 by sputtering, evaporation and electroplating.

[0081] Another embodiment of the present application provides a secondary battery including the double-cell structure, which includes the composite current collector tab connection structure.

[0082] Specifically, the secondary battery further includes a shell, which is a semi-closed shell with one end open. The double-cell structure is placed in the shell through the opening, and the opening is closed to obtain the secondary battery of the present application. The double-cell structure in the secondary battery provided by the present application includes the composite current collector tab connection structure. The end portions of the plurality of second tabs 5 are folded and inserted one by one between the plurality of first tabs 4. In the present application, the electrical connection between the plurality of first tabs 4 and the plurality of second tabs 5 is achieved by folding and inserting the plurality of second tabs 5 between the plurality of first tabs 4, thereby connecting the electrical connection paths of the first metal layer 31, the second metal layer 32 and the polymer layer 33. Compared with the prior art, the present application achieves the connection of current in the composite current collector by changing the composite current collector tab connection structure without additional conductive sheets. In addition, the present application avoids adding new conductive sheets, which is beneficial to reducing the overall weight of the battery and improving the energy density of the battery.

[0083] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A composite current collector tab connection structure, characterized in that, Includes multiple first pole ears (4) and multiple second pole ears (5); The first electrode (4) and the second electrode (5) are both composite layer structures (3). The composite layer structure (3) includes a first metal layer (31), a second metal layer (32) and a polymer layer (33). The polymer layer (33) is placed between the first metal layer (31) and the second metal layer (32). The first ends of a plurality of first electrodes (4) are stacked, and the second ends of a plurality of first electrodes (4) are spaced apart along the thickness direction of the first electrodes (4); The first ends of multiple second pole pieces (5) are stacked and located outside the first end of the outermost first pole piece (4); The second electrode (5) includes a straight portion (51), a bent portion (52) and an extension portion (53) connected in sequence; the straight portions (51) of a plurality of second electrode (5) are stacked and located outside the first electrode (4); the extension portion (53) of one second electrode (5) is stacked outside the outermost first electrode (4); the extension portions (53) of the remaining second electrode (5) are inserted between a plurality of first electrode (4) at intervals, so that the plurality of extension portions (53) and the plurality of first electrode (4) are staggered and stacked; The first metal layer (31) and / or the second metal layer (32) at the second end of the second electrode (5) are electrically connected to the first metal layer (31) and / or the second metal layer (32) at the opposite end of the first electrode (4).

2. The composite current collector tab connection structure according to claim 1, characterized in that, The straight portion (51), the first electrode (4), and the extension portion (53) are arranged in parallel.

3. The composite current collector tab connection structure according to claim 1, characterized in that, The composite current collector tab connection structure includes a first fixed connection area (A) and a second fixed connection area (B). In the first fixed connection area (A), a plurality of extensions (53), a plurality of first tabs (4) and a plurality of straight portions (51) are stacked and fixedly connected. In the second fixed connection area (B), a plurality of first tabs (4) and a plurality of straight portions (51) are stacked and fixedly connected.

4. The composite current collector tab connection structure according to claim 3, characterized in that, The fixed connection is achieved by welding.

5. The composite current collector tab connection structure according to claim 3, characterized in that, The ends of multiple first tabs (4) and multiple second tabs (5) are stacked alternately and then fixedly connected at the staggered stacking positions to form the first fixed connection area (A). Multiple second electrodes (5) are folded outside the first fixed connection area (A) so that the main body of multiple second electrodes (5) and the main body of multiple first electrodes (4) are stacked on each other and fixedly connected at the stacked position so that multiple first electrodes (4) and multiple second electrodes (5) are fixedly connected as one unit.

6. The composite current collector tab connection structure according to claim 1, characterized in that, It also includes a third electrode (6) for external connection; the third electrode (6) is fixedly connected to the second electrode (5) located on the outermost side.

7. The composite current collector tab connection structure according to claim 6, characterized in that, The third electrode tab (6) is a hard electrode tab welded to the outermost second electrode tab (5).

8. A composite current collector tab connection structure according to any one of claims 1-6, characterized in that, The first metal layer (31) and the second metal layer (32) of the first electrode (4) are copper foil or aluminum foil; The first metal layer (31) and the second metal layer (32) of the second electrode (5) are copper foil or aluminum foil.

9. A dual-cell structure, characterized in that, The battery includes a first battery cell (1) and a second battery cell (2). The first battery cell (1) includes a plurality of first positive tabs (11) and a plurality of first negative tabs (12). The second battery cell (2) includes a plurality of second positive tabs (21) and a plurality of second negative tabs (22). The first battery cell (1) and the second battery cell (2) are stacked together. The plurality of first positive tabs (11) and the plurality of second positive tabs (21) are connected by a composite current collector tab connection structure as described in any one of claims 1 to 4, and the plurality of first negative tabs (12) and the plurality of second negative tabs (22) are connected; or, Multiple first positive tabs (11) and multiple second positive tabs (21) are connected, and multiple first negative tabs (12) and multiple second negative tabs (22) adopt the composite current collector tab connection structure as described in any one of claims 1 to 8; or, The plurality of first positive tabs (11) and the plurality of second positive tabs (21) adopt the composite current collector tab connection structure as described in any one of claims 1 to 4, and the plurality of first negative tabs (12) and the plurality of second negative tabs (22) adopt the composite current collector tab connection structure as described in any one of claims 1 to 8.

10. A dual-cell structure according to claim 9, characterized in that, The first cell (1) and the second cell (2) are laminated cells.

11. A dual-cell structure according to claim 9, characterized in that, The first cell (1) includes a plurality of first positive electrode plates, a plurality of first negative electrode plates, and a first separator spaced between any adjacent first positive electrode plates and first negative electrode plates. The first positive electrode tab (11) extends from one end or one side of the first positive electrode plate, and the first negative electrode tab (12) correspondingly extends from one end or one side of the first negative electrode plate; and / or, The second cell (2) includes a plurality of second positive plates, a plurality of second negative plates and a second separator spaced between any adjacent second positive plates and second negative plates. The second positive tab (21) is led out from one end or one side of the second positive plate, and the second negative tab (22) is led out from one end of the second negative plate accordingly.

12. A dual-cell structure according to claim 11, characterized in that, The first positive electrode includes a first positive current collector, the first negative electrode includes a first negative current collector, the second positive electrode includes a second positive current collector, and the second negative electrode includes a second negative current collector. The first positive current collector, the first negative current collector, the second positive current collector, and the second negative current collector are all composite layer structures (3). The first positive electrode tab (11) and the first positive current collector are integral structures. The first negative electrode tab (12) and the first negative current collector are integral structures. The second positive electrode tab (21) and the second positive current collector are integral structures. The second negative electrode tab (22) and the second negative current collector are integral structures.

13. A secondary battery, characterized in that, Includes the dual-cell structure as described in any one of claims 9 to 12.

Images