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

Abstract

The invention provides a composite current collector tab connecting structure, a preparation method, a double-cell structure and a secondary battery in order to solve the problem that in the prior art, a middle polymer layer of a composite current collector affects circuit connection of metal layers on the two sides of the composite current collector. The composite current collector tab connecting structure comprises a plurality of first tabs and a plurality of second tabs, each of the first tabs and the second tabs is of a composite layer structure, each composite layer structure comprises a first metal layer, a second metal layer and a polymer layer, and each polymer layer is arranged between the corresponding first metal layer and the corresponding second metal layer. And the end parts of the plurality of second tabs are folded and are inserted among the plurality of first tabs at intervals one by one. According to the composite current collector tab connection structure provided by the invention, the plurality of second tabs are turned over and inserted among the plurality of first tabs at intervals, so that the plurality of first tabs are electrically connected with the plurality of second tabs, and an electric connection path of the composite layer structure is further communicated.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion battery manufacturing, and specifically relates to a composite current collector pole ear connection structure, a preparation method, a dual-cell structure and a secondary battery. Background Art

[0002] The current collector has the function of carrying the active materials of the battery, collecting the current generated by the active materials of the battery and outputting it, so the current collector has a great influence on the performance of lithium-ion batteries such as capacity, rate and cycle. In order to improve the energy density of the battery, reducing the thickness of the current collector has become the main development trend, but too thin a current collector will not only increase the cost, but also easily cause problems such as wrinkling and breaking in the process. Therefore, the metal current collector cannot be infinitely thinned. The new composite structure current collector has obvious advantages in improving battery safety, energy density, and high cycle life.

[0003] The composite current collector is a new type of composite foil with a "sandwich" structure, with a polymer base film in the middle and aluminum or copper plated on both sides of the base film, corresponding to the aluminum foil and copper foil of the positive and negative electrodes of the lithium battery. Since the upper and lower metal layers of the composite current collector are not connected, it is currently necessary to connect the upper and lower metal coatings through a conductive sheet and then weld them to the pole ear. This connection method requires the metal layer on each side to be connected to the conductive sheet, which will not only increase the weight of the battery and reduce the battery energy density, but also affect the welding reliability. In severe cases, the welding will not be firm and perforated, thus affecting the electrical performance. Summary of the invention

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

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: Provided is a composite current collector tab connection structure, comprising a plurality of first tabs and a plurality of second tabs; The first electrode tab and the second electrode tab are both composite layer structures, the composite layer structure comprising a first metal layer, a second metal layer and a polymer layer, the polymer layer being disposed between the first metal layer and the second metal layer; The first ends of the plurality of first pole tabs are stacked, and the second ends of the plurality of first pole tabs are spaced apart along the thickness direction of the first pole tabs; The first ends of the plurality of second pole lugs are stacked and located outside the first end of the outermost first pole lug; the ends of the second ends of the plurality of second pole lugs are folded and inserted between the second ends of the plurality of first pole lugs one by one and at intervals, and / or stacked outside the second end of the outermost first pole lug; The first metal layer and / or the second metal layer at the end of the second end of the second electrode tab is electrically connected to the first metal layer and / or the second metal layer at the end of the first electrode tab opposite thereto.

[0006] Optionally, the second pole ear includes a straight portion, a bent portion and an extended portion, a plurality of the straight portions are stacked and located on the outside of the first pole ear, a plurality of the bent portions are connected one-to-one with a plurality of the straight portions and a plurality of the extended portions, a plurality of the extended portions are inserted between a plurality of the first pole ears at intervals and / or stacked on the outside of the outermost first pole ear, and a plurality of the extended portions and a plurality of the first pole ears are staggered and stacked one by one.

[0007] Optionally, the straight portion, the first electrode tab and the extending portion are arranged in parallel.

[0008] Optionally, the composite current collector pole ear connection structure includes a first fixed connection area and a second fixed connection area, in which a plurality of the extension portions, a plurality of the first pole ears and a plurality of the straight portions are stacked and fixedly connected; in the second fixed connection area, a plurality of the first pole ears and a plurality of the straight portions are stacked and fixedly connected.

[0009] Optionally, the fixed connection is achieved by welding.

[0010] Optionally, the method for preparing the dual-cell structure comprises the following steps: Alternately stacking the ends of the plurality of first pole tabs and the ends of the plurality of second pole tabs one by one, and fixedly connecting them at the alternately stacked positions to form the first fixed connection area; The plurality of second pole tabs are folded outside the first fixed connection area so that the bodies of the plurality of second pole tabs are stacked with the bodies of the plurality of first pole tabs, and fixedly connected at the stacking position so that the plurality of first pole tabs and the plurality of second pole tabs are fixedly connected as one.

[0011] Optionally, it further includes a third pole lug for external connection; the third pole lug is fixedly connected to the second pole lug located at the outermost side.

[0012] Optionally, the third pole lug is a hard pole lug welded to the outermost second pole lug. Optionally, the first metal layer and the second metal layer of the first electrode tab are copper foil or aluminum foil; The first metal layer and the second metal layer of the second electrode tab are copper foil or aluminum foil.

[0013] On the other hand, the present application provides a dual-cell structure, including a first cell and a second cell, wherein the first cell includes a plurality of first positive electrodes and a plurality of first negative electrodes, and the second cell includes a plurality of second positive electrodes and a plurality of second negative electrodes, and the first cell and the second cell are stacked; The plurality of first positive electrode tabs and the plurality of second positive electrode tabs adopt the composite current collector tab connection structure, and the plurality of first negative electrode tabs and the plurality of second negative electrode tabs are connected; and / or, A plurality of the first positive electrode tabs and a plurality of the second positive electrode tabs are connected, and a plurality of the first negative electrode tabs and a plurality of the second negative electrode tabs adopt the composite current collector tab connection structure; and / or, The plurality of first positive electrode tabs and the plurality of second positive electrode tabs adopt the composite current collector electrode tab connection structure, and the plurality of first negative electrode tabs and the plurality of second negative electrode tabs adopt the composite current collector electrode tab connection structure.

[0014] Optionally, the first battery cell and the second battery cell are laminated battery cells.

[0015] Optionally, the first battery cell includes a plurality of first positive electrode sheets, a plurality of first negative electrode sheets, and a first separator spaced between any adjacent first positive electrode sheets and first negative electrode sheets, the first positive electrode ear is led out from one end or one side of the first positive electrode sheet, and the first negative electrode ear is correspondingly led out from one end or one side of the first negative electrode sheet; and / or, The second battery cell includes a plurality of second positive electrode sheets, a plurality of second negative electrode sheets and a second separator spaced between any adjacent second positive electrode sheets and second negative electrode sheets. The second positive electrode ear is led out from one end or one side of the second positive electrode sheet, and the second negative electrode ear is correspondingly led out from one end of the second negative electrode sheet.

[0016] Optionally, the first positive electrode sheet includes a first positive current collector, the first negative electrode sheet includes a first negative current collector, the second positive electrode sheet includes a second positive current collector, the second negative electrode sheet 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, the first positive electrode ear and the first positive current collector are an integrated structure, the first negative electrode ear and the first negative current collector are an integrated structure, the second positive electrode ear and the second positive current collector are an integrated structure, and the second negative electrode ear and the second negative current collector are an integrated structure.

[0017] On the other hand, the present invention provides a secondary battery, comprising the dual-cell structure, wherein the dual-cell structure comprises the composite current collector tab connection structure.

[0018] The beneficial effects of the present invention are: In the dual-cell structure provided by the present invention, the first ends of the plurality of first pole ears are stacked, the first ends of the plurality of first pole ears are spaced apart, the first ends of the plurality of second pole ears are stacked and located outside the first end of the outermost first pole ear, the end portions of the second ends of the plurality of second pole ears are folded over and inserted one by one between the plurality of first pole ears at intervals, and / or stacked on the outer side of the outermost first pole ear, that is, in the present application, the plurality of first pole ears are electrically connected to the plurality of second pole ears by means of the folded and spaced insertion between the plurality of first pole ears and / or stacked on the outer side of the outermost first pole ear, thereby connecting the electrical connection paths of the first metal layer, the second metal layer and the polymer layer. Compared with the prior art, the present invention realizes the connection of current in the composite current collector by changing the connection structure of the plurality of first pole ears and the plurality of second pole ears without adding additional conductive sheets, and secondly avoids adding new conductive sheets, which is conducive to reducing the overall battery weight and thus improving the battery energy density. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the connection structure of the composite current collector tab provided by the present invention; Figure 2 is a schematic diagram of the composite current collector structure provided by the present invention; Figure 3 This is an exploded view of the dual-cell structure provided by the present invention; Figure 4 yes Figure 3 Enlarged view of point C in the middle; Figure 5 Schematic diagram of the stacking welding of the first pole tab and the second pole tab provided by the present invention; Figure 6 It is a schematic diagram of bending the first pole tab and the second pole tab layer at the non-stacked position provided by the present invention; Figure 7 It is a schematic diagram of the dual-cell structure and the third pole ear welding structure provided by the present invention.

[0020] The reference numerals in the drawings of the specification are as follows: 1. First battery cell; 11. First positive electrode ear; 12. First negative electrode ear; 2. Second battery cell; 21. Second positive electrode ear; 22. Second negative electrode ear; 3. Composite layer structure; 31. First metal layer; 32. Second metal layer; 33. Polymer layer; 4. First electrode ear; 5. Second electrode ear; 51. Straight portion; 52. Bend portion; 53. Extension portion; A. First fixed connection area; B. Second fixed connection area; 6. Third electrode ear. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Reference Figure 1 , an embodiment of the present invention provides a dual-cell structure, including a plurality of first pole tabs 4 and a plurality of second pole tabs 5; The first pole tab 4 and the second pole tab 5 are both composite layer structures 3, and the composite layer structure 3 includes a first metal layer 31, a second metal layer 32 and a polymer layer 33, and the polymer layer 33 is disposed between the first metal layer 31 and the second metal layer 32 ( Figure 2 ); The first ends of the plurality of first pole tabs 4 are stacked, and the second ends of the plurality of first pole tabs 4 are spaced apart along the thickness direction of the first pole tabs; The first ends of the plurality of second pole tabs 5 are stacked and located outside the first end of the outermost first pole tab 4; the ends of the second ends of the plurality of second pole tabs 5 are folded and inserted between the second ends of the plurality of first pole tabs 4 one by one and / or stacked outside the second end of the outermost first pole tab 4; The first metal layer 31 and / or the second metal layer 32 at the end of the second end of the second electrode tab 5 is electrically connected to the first metal layer 31 and / or the second metal layer 32 at the end of the first electrode tab 4 opposite thereto.

[0025] In the present application, multiple first pole ears 4 are electrically connected to multiple second pole ears 5 by inserting the folded intervals of multiple second pole ears 5 between multiple first pole ears 4 and / or stacking them on the outside of the outermost first pole ear 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 invention realizes the connection of current in the composite current collector by changing the connection structure of multiple first pole ears 4 and multiple second pole ears 5 without adding additional conductive sheets. Secondly, avoiding the addition of new conductive sheets is beneficial to reducing the overall battery weight and thus improving the battery energy density.

[0026] In one embodiment, the second pole lug 5 includes a straight portion 51, a bent portion 52 and an extended portion 53, a plurality of the straight portions 51 are stacked and located on the outside of the first pole lug 4, a plurality of the bent portions 52 are connected one by one to the plurality of the straight portions 51 and the plurality of the extended portions 53, a plurality of the extended portions 53 are inserted between the plurality of the first pole lugs 4 at intervals, and / or are stacked on the outside of the outermost first pole lug 4, and a plurality of the extended portions 53 and a plurality of the first pole lugs 4 are staggered and stacked one by one.

[0027] Reference Figure 1 Specifically, the arrangement of the bending portion 52 facilitates the electrical connection between the second pole lug 5 and the first pole lug 4. In addition, the plurality of extension portions 53 are inserted between the plurality of first pole lugs 4 at intervals, and the plurality of extension portions 53 and the plurality of first pole lugs 4 are staggered and stacked one by one. At this time, the plurality of extension portions 53 are stacked and covered on the first pole lug 4, which is beneficial to further increase the contact surface when the second pole lug 5 is connected to the first pole lug 4, and at the same time, it can improve the welding reliability of the pole lug in the subsequent bending and welding process, and avoid the occurrence of problems such as cold welding.

[0028] In one embodiment, the straight portion 51 , the first electrode tab 4 and the extending portion 53 are arranged in parallel.

[0029] In one embodiment, the composite current collector pole ear connection structure includes a first fixed connection area A and a second fixed connection area B. In the first fixed connection area A, multiple extension portions 53, multiple first pole ears 4 and multiple straight portions 51 are stacked and fixedly connected; in the second fixed connection area B, multiple first pole ears 4 and multiple straight portions 51 are stacked and fixedly connected.

[0030] The first fixed connection area A further includes a first region and a second region. In the first region, a plurality of the extension portions 53 and a plurality of the first pole tabs 4 are stacked alternately. In the second region, a plurality of the straight portions 51 are stacked mutually.

[0031] In one embodiment, the fixed connection is achieved by welding.

[0032] Another embodiment of the present application provides a method for preparing a dual-cell structure, comprising the following steps: The ends of the plurality of first pole tabs 4 and the ends of the plurality of second pole tabs 5 are stacked alternately one by one, and fixedly connected at the staggered stacking positions to form the first fixed connection area A; The plurality of second pole tabs 5 are folded outside the first fixed connection area A so that the main bodies of the plurality of second pole tabs 5 and the main bodies of the plurality of first pole tabs 4 are stacked parallel to each other, and fixedly connected at the stacking position so that the plurality of first pole tabs 4 and the plurality of second pole tabs 5 are fixedly connected as one.

[0033] Reference Figures 5 and 6 Specifically, firstly, the ends of the plurality of first pole tabs 4 and the ends of the plurality of second pole tabs 5 are alternately stacked one by one, and then a first welding is performed at the stacking position, and this operation can realize the electrical connection between the first pole tab 4 and the second pole tab 5; The plurality of second pole tabs 5 are folded outside the first fixed connection area A so that the main bodies of the plurality of second pole tabs 5 and the plurality of first pole tabs 4 are stacked parallel to each other, and then a second welding is performed at the stacking position. The second welding welds the first pole tab 4 and the plurality of second pole tabs 5 into one, thereby reducing the connection impedance and improving the reliability of welding.

[0034] Reference Figure 7 In one embodiment, it further includes a third pole lug 6 for external connection; the third pole lug 6 is fixedly connected to the second pole lug 5 located at the outermost side.

[0035] Specifically, the operation of welding the hard electrode tab on the outermost second electrode tab 5 can effectively improve the structural stability and conductive performance of the secondary battery, thereby improving the service life and safety of the battery.

[0036] Specifically, the hard pole tab is generally made of a hard material. In the present application, the hard pole tab may be made of a metal material such as aluminum or copper.

[0037] In one embodiment, the first metal layer 31 and the second metal layer 32 of the first electrode tab 4 are copper foil or aluminum foil; The first metal layer 31 and the second metal layer 32 of the second electrode tab 5 are copper foil or aluminum foil.

[0038] Reference Figure 3~4Another embodiment of the present application provides a dual-cell structure, including a first cell 1 and a second cell 2, wherein the first cell 1 includes a plurality of first positive electrodes 11 and a plurality of first negative electrodes 12, and the second cell 2 includes a plurality of second positive electrodes 21 and a plurality of second negative electrodes 22, and the first cell 1 and the second cell 2 are stacked; A plurality of the first negative electrode tabs 12 and a plurality of the second negative electrode tabs 22 are connected; and / or, a plurality of the first positive electrode tabs 11 and a plurality of the second positive electrode tabs 21 are connected, and a plurality of the first negative electrode tabs 12 and a plurality of the second negative electrode tabs 22 adopt the composite current collector tab connection structure; and / or, a plurality of the first positive electrode tabs 11 and a plurality of the second positive electrode tabs 21 adopt the composite current collector tab connection structure, and a plurality of the first negative electrode tabs 12 and a plurality of the second negative electrode tabs 22 adopt the composite current collector tab connection structure.

[0039] Specifically, among the multiple first positive ears 11 and the multiple first negative ears 12 on the first battery cell 1, the first positive ear 11 is used to conduct the current generated by the positive electrode of the battery cell to the outside, and the first negative ear 12 is used to conduct the negative electrode current of the battery cell; by connecting the multiple first negative ears 12 and the multiple second negative ears 22 to each other, the negative electrode current can be smoothly conducted between the two battery cells. Similarly, the multiple first positive ears 11 and the multiple second positive ears 21 can also be connected to realize the connection of the current path in the positive direction of the two battery cells, ensuring that the current can flow in an orderly manner in both the positive and negative electrode circuits.

[0040] The multiple first negative pole ears 12 and the multiple second negative pole ears 22 use the composite current collector pole ear connection structure to make the conduction of the negative pole current between the two battery cells more efficient, stable and more structurally reasonable; similarly, the multiple first positive pole ears 11 and the multiple second positive pole ears 21 can also use the composite current collector pole ear connection structure to achieve connectivity, further improving the positive current conduction performance. In addition, the multiple first positive pole ears 11 and the multiple second positive pole ears 21, the multiple first negative pole ears 12 and the multiple second negative pole ears 22 all use the composite current collector pole ear connection structure at the same time, and the composite current collector pole ear connection structure is used to improve the electrical connection characteristics of the entire dual-cell structure, and the conduction effect of the current in the positive and negative circuits is optimized to the greatest extent, so that the entire dual-cell structure reaches a better state in terms of electrical performance.

[0041] Specifically, the first positive electrode ear 11 and the first negative electrode ear 12 are the first electrode ear 4, the plurality of second positive electrode ears 21 and the plurality of second negative electrode ears 22 are the second electrode ears 5, the plurality of first positive electrode ears 11, the plurality of first negative electrode ears 12 and the plurality of second positive electrode ears 21, the plurality of second negative electrode ears 22 are led out in the same direction, and then the ends of the plurality of second positive electrode ears 21 are folded and inserted one by one between the plurality of first positive electrode ears 11, and the ends of the plurality of second negative electrode ears 22 are folded and inserted one by one between the plurality of first negative electrode ears 12.

[0042] In one embodiment, the first battery cell 1 and the second battery cell 2 are laminated battery cells.

[0043] In the dual-cell structure, the first cell 1 and the second cell 2 are in the form of stacked cells. During subsequent operations such as connecting the tabs, the good internal structure uniformity of the stacked cells can make the current flow between the cells and the tabs and through the tabs more smoothly and stably, further improving the electrical performance and safety of the entire dual-cell structure.

[0044] In one embodiment, the first battery cell 1 includes a plurality of first positive electrode sheets, a plurality of first negative electrode sheets, and a first separator spaced between any adjacent first positive electrode sheets and first negative electrode sheets, the first positive electrode ear 11 is led out from one end or one side of the first positive electrode sheet, and the first negative electrode ear 12 is correspondingly led out from one end or one side of the first negative electrode sheet; and / or, the second battery cell 2 includes a plurality of second positive electrode sheets, a plurality of second negative electrode sheets, and a second separator spaced between any adjacent second positive electrode sheets and second negative electrode sheets, the second positive electrode ear 21 is led out from one end or one side of the second positive electrode sheet, and the second negative electrode ear 22 is correspondingly led out from one end of the second negative electrode sheet.

[0045] The first diaphragm and the second diaphragm can be conventional diaphragms, or ceramic diaphragms, polymer diaphragms, non-woven fabrics, inorganic-organic composite diaphragms, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP and triple-layer PP / PE / PP diaphragms.

[0046] In one embodiment, the first positive electrode sheet includes a first positive current collector, the first negative electrode sheet includes a first negative current collector, the second positive electrode sheet includes a second positive current collector, the second negative electrode sheet 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 a composite layer structure 3, the first positive electrode ear 11 and the first positive current collector are an integrated structure, the first negative electrode ear 12 and the first negative current collector are an integrated structure, the second positive electrode ear 21 and the second positive current collector are an integrated structure, and the second negative electrode ear 22 and the second negative current collector are an integrated structure.

[0047] It should be noted that in order to improve the energy density of the battery, a commonly used method is to achieve this by reducing the thickness of the current collector. However, a current collector that is too thin cannot provide good mechanical strength and support, and therefore is prone to wrinkling, breaking, and other problems in subsequent process steps.

[0048] 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 a composite layer structure 3, that is, the first metal layer 31 and the second metal layer 32 as the metal conductive layer of the composite layer structure 3 are composited with the polymer layer 33 to form a composite current collector with a multi-layer composite structure. The composite current collector with a multi-layer composite structure can provide better support and mechanical strength than traditional current collectors under the premise of meeting the collection current.

[0049] The polymer layer 33 may be a PET film layer, a PP film layer or a PI film layer. Due to the use of high molecular weight polymer materials in the polymer layer 33, the mass of the formed composite current collector is lighter than that of a traditional foil current collector of the same thickness, which is beneficial to reduce the overall weight of the assembled lithium-ion battery. On the other hand, when the volume of the battery cell remains unchanged, a lighter and thinner composite current collector can increase the filling amount of active materials, thereby improving the energy density of the battery.

[0050] The first metal layer 31 and the second metal layer 32 on both sides of the polymer layer 33 may be plated on both sides of the polymer layer 33 by sputtering, evaporation, water electroplating or the like.

[0051] Another embodiment of the present application provides a secondary battery, including the dual-cell structure, wherein the dual-cell structure includes the composite current collector tab connection structure.

[0052] Specifically, the secondary battery also includes a shell, which is a semi-closed shell with an opening at one end. The dual-cell structure is placed in the shell through the opening, and the opening is closed to obtain the secondary battery described in the present application; the dual-cell structure described in the secondary battery provided by the present application includes the composite current collector pole ear connection structure, and the ends of multiple second pole ears 5 are folded and inserted one by one between multiple first pole ears 4 at intervals, that is, in the present application, multiple first pole ears 4 are electrically connected to multiple second pole ears 5 by folding multiple second pole ears 5 and inserting them between multiple first pole ears 4 at intervals, 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 invention realizes the connection of current in the composite current collector by changing the composite current collector pole ear connection structure without adding additional conductive sheets, and secondly avoids adding new conductive sheets, which is beneficial to reducing the overall battery weight and thus improving the battery energy density.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite current collector tab connection structure, characterized in that: It comprises a plurality of first pole tabs (4) and a plurality of second pole tabs (5); The first pole lug (4) and the second pole lug (5) are both composite layer structures (3), the composite layer structure (3) comprising 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); The first ends of the plurality of first pole tabs (4) are stacked, and the second ends of the plurality of first pole tabs (4) are spaced apart along the thickness direction of the first pole tabs (4); The first ends of the plurality of second pole tabs (5) are stacked and located outside the first end of the outermost first pole tab (4); the ends of the second ends of the plurality of second pole tabs (5) are folded over and inserted one by one between the second ends of the plurality of first pole tabs (4) at intervals, and / or stacked outside the second end of the outermost first pole tab (4); The first metal layer (31) and / or the second metal layer (32) at the end of the second end of the second pole lug (5) is electrically connected to the first metal layer (31) and / or the second metal layer (32) at the end of the first pole lug (4) opposite thereto.

2. The composite current collector tab connection structure according to claim 1, characterized in that: The second pole lug (5) comprises a straight portion (51), a bent portion (52) and an extended portion (53); a plurality of the straight portions (51) are stacked and located outside the first pole lug (4); a plurality of the bent portions (52) are connected one by one to the plurality of the straight portions (51) and the plurality of the extended portions (53); a plurality of the extended portions (53) are inserted between the plurality of the first pole lugs (4) at intervals and / or stacked on the outside of the outermost first pole lug (4); a plurality of the extended portions (53) and a plurality of the first pole lugs (4) are stacked one by one in an alternating manner.

3. The composite current collector tab connection structure according to claim 2, characterized in that: The straight portion (51), the first pole lug (4) and the extending portion (53) are arranged in parallel.

4. The composite current collector tab connection structure according to claim 2, characterized in that: The composite current collector electrode tab connection structure comprises a first fixed connection area (A) and a second fixed connection area (B), wherein in the first fixed connection area (A), a plurality of the extension portions (53), a plurality of the first electrode tabs (4) and a plurality of the straight portions (51) are stacked and fixedly connected; and in the second fixed connection area (B), a plurality of the first electrode tabs (4) and a plurality of the straight portions (51) are stacked and fixedly connected.

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

6. The method for preparing a composite current collector tab connection structure according to claim 4, characterized in that: The steps are as follows: The ends of the plurality of first pole tabs (4) and the ends of the plurality of second pole tabs (5) are stacked one by one in an alternating manner, and fixedly connected at the alternating stacking positions to form the first fixed connection area (A); The plurality of second pole tabs (5) are folded outside the first fixed connection area (A) so that the main bodies of the plurality of second pole tabs (5) and the main bodies of the plurality of first pole tabs (4) are stacked on each other, and fixedly connected at the stacked positions so that the plurality of first pole tabs (4) and the plurality of second pole tabs (5) are fixedly connected as one body.

7. The composite current collector tab connection structure according to claim 1, characterized in that: It also comprises a third pole lug (6) for external connection; the third pole lug (6) is fixedly connected to the second pole lug (5) located at the outermost side.

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

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

10. A dual-cell structure, characterized in that: Comprising a first battery cell (1) and a second battery cell (2), the first battery cell (1) comprising a plurality of first positive electrode tabs (11) and a plurality of first negative electrode tabs (12), the second battery cell (2) comprising a plurality of second positive electrode tabs (21) and a plurality of second negative electrode tabs (22), the first battery cell (1) and the second battery cell (2) being stacked; The plurality of first positive electrode tabs (11) and the plurality of second positive electrode tabs (21) adopt the composite current collector tab connection structure according to any one of claims 1 to 4, and the plurality of first negative electrode tabs (12) and the plurality of second negative electrode tabs (22) are connected; and / or, A plurality of the first positive electrode tabs (11) and a plurality of the second positive electrode tabs (21) are connected, and a plurality of the first negative electrode tabs (12) and a plurality of the second negative electrode tabs (22) adopt the composite current collector tab connection structure according to any one of claims 1 to 9; and / or, The plurality of first positive electrode tabs (11) and the plurality of second positive electrode tabs (21) adopt the composite current collector tab connection structure as claimed in any one of claims 1 to 4, and the plurality of first negative electrode tabs (12) and the plurality of second negative electrode tabs (22) adopt the composite current collector tab connection structure as claimed in any one of claims 1 to 9.

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

12. A dual-cell structure according to claim 10, characterized in that: The first battery cell (1) comprises a plurality of first positive electrode sheets, a plurality of first negative electrode sheets and a first separator spaced between any adjacent first positive electrode sheets and first negative electrode sheets, the first positive electrode tab (11) is led out from one end or one side of the first positive electrode sheet, and the first negative electrode tab (12) is correspondingly led out from one end or one side of the first negative electrode sheet; and / or, The second battery cell (2) comprises a plurality of second positive electrode sheets, a plurality of second negative electrode sheets and a second separator spaced between any adjacent second positive electrode sheets and second negative electrode sheets, the second positive electrode tab (21) is led out from one end or one side of the second positive electrode sheet, and the second negative electrode tab (22) is correspondingly led out from one end of the second negative electrode sheet.

13. A dual-cell structure according to claim 12, characterized in that: The first positive electrode sheet comprises a first positive current collector, the first negative electrode sheet comprises a first negative current collector, the second positive electrode sheet comprises a second positive current collector, the second negative electrode sheet 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 a composite layer structure (3), the first positive electrode ear (11) and the first positive current collector are an integrated structure, the first negative electrode ear (12) and the first negative current collector are an integrated structure, the second positive electrode ear (21) and the second positive current collector are an integrated structure, and the second negative electrode ear (22) and the second negative current collector are an integrated structure.

14. A secondary battery, characterized in that: The dual-cell structure comprises the dual-cell structure described in any one of claims 10 to 13, wherein the dual-cell structure comprises the composite current collector tab connection structure described in any one of claims 1 to 9.

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