A composite foil material and its preparation method and application

Abstract

The present invention belongs to the field of battery technology, and provides a composite foil material and a preparation method and application thereof, wherein the composite foil material comprises a composite layer, and the composite layer comprises a base film and metal layers on both sides of the base film; a first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side, and the first metal mesh and the second metal mesh are connected on the side of the composite layer; the composite foil material also comprises a first metal fixed film covering the first metal mesh and contacting the composite layer in the mesh of the first metal mesh, and a second metal fixed film covering the second metal mesh and contacting the composite layer in the mesh of the second metal mesh. The composite foil material of the present invention is conducive to improving the peeling force of the pole piece through the arrangement of the metal mesh, and can also improve the wetting effect of the pole piece. In addition, the multilayer structure of the composite foil material is mutually conductive, and the composite foil material has excellent electrical conductivity and thermal conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a composite foil material and a preparation method and application thereof. Background Art

[0002] As an important material, composite foil is widely used in energy storage devices such as batteries and capacitors. Composite copper / aluminum foil for lithium batteries is a composite material consisting of a 1µm copper / aluminum layer, a few µm PET / PP base film and a 1µm copper / aluminum layer. This composite material has a light weight and good safety performance, which can improve the energy density and safety of the battery.

[0003] The existing composite copper / aluminum foil is used as a battery current collector. After the positive / negative electrode slurry is coated on the surface and rolled, its peeling force is low, which is not conducive to the long-term recycling of the battery core. In addition, the 1-micron metal layer is not conducive to the welding of the composite foil, and the PET / PP insulation layer in the middle of the composite foil prevents the different pole pieces from conducting with each other. Therefore, the problems or shortcomings of the existing composite foil in the field of batteries have limited the further application and development of the composite foil. Summary of the invention

[0004] The object of the present invention is to provide a composite foil material and a preparation method and application thereof. The composite foil material is advantageous in retaining more slurry when the electrode slurry is applied by setting a metal mesh, thereby facilitating the preparation of thick electrodes, improving the peeling force of the electrode sheet, and also improving the wetting effect of the electrode sheet. In addition, the multilayer structure of the composite foil material is mutually conductive, and the composite foil material has excellent electrical conductivity and thermal conductivity.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a base film and metal layers on both sides of the base film.

[0007] A first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side. The first metal mesh and the second metal mesh are connected at the side of the composite layer.

[0008] The composite foil material further includes a first metal fixing film, which covers the first metal mesh and contacts the composite layer in the mesh holes of the first metal mesh, so that the composite layer is fixed to the first metal mesh.

[0009] The composite foil further includes a second metal fixing film, which covers the second metal mesh and contacts the composite layer in the mesh holes of the second metal mesh, so that the composite layer is fixed to the second metal mesh.

[0010] The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

[0011] Preferably, the thickness of the first metal fixing film is smaller than the thickness of the first metal mesh, and the thickness of the second metal fixing film is smaller than the thickness of the second metal mesh.

[0012] Preferably, the thickness of the first metal fixing film is 5%-10% of the thickness of the first metal mesh, and the thickness of the second metal fixing film is 5%-10% of the thickness of the second metal mesh.

[0013] Preferably, the thickness of the first metal mesh and the second metal mesh are independently 3 μm-5 μm.

[0014] Preferably, the first metal mesh and the second metal mesh are independently copper mesh or aluminum mesh, and the metal material of the first metal mesh and the second metal mesh is the same as the metal material of the metal layer.

[0015] Preferably, the first metal fixing film and the second metal fixing film are independently copper films or aluminum films.

[0016] Preferably, the base film comprises a polymer film layer, and the metal layer comprises a copper layer or an aluminum layer.

[0017] In a second aspect, the present invention provides a method for preparing the composite foil as described in the first aspect, the preparation method comprising the following steps:

[0018] The first metal mesh is arranged on one side of the composite layer, and the second metal mesh is arranged on the other side of the composite layer, and then hot pressing is performed.

[0019] After hot pressing, a first metal fixing film is arranged on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixing film is arranged on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh.

[0020] Finally, the first metal mesh and the second metal mesh on the side of the composite layer are connected to obtain the composite foil.

[0021] Preferably, the methods of providing the first metal fixed film and the second metal fixed film respectively and independently include magnetron sputtering or vacuum evaporation.

[0022] Preferably, the method of connecting the first metal mesh and the second metal mesh on the side of the composite layer includes welding.

[0023] In a third aspect, the present invention provides an electrode plate, wherein the electrode plate comprises the composite foil material as described in the first aspect.

[0024] In a fourth aspect, the present invention provides a battery, comprising the composite foil as described in the first aspect, or the electrode plate as described in the third aspect.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention can improve the electrical conductivity and thermal conductivity of the composite foil by setting the first metal mesh and the second metal mesh, and can also improve the peeling force between the active material layer and the composite foil under the condition of the same active material loading amount, and is also conducive to the preparation of thick electrodes to meet the needs of some special applications.

[0027] (2) The first metal fixing film and the second metal fixing film of the present invention can fix the composite layer and the first metal mesh and the second metal mesh together, so that the entire composite foil is a whole, and the first metal mesh and the second metal mesh are connected at the side of the composite layer, so that the entire composite foil can be conductive.

[0028] (3) The composite foil of the present invention can also improve the porosity and wetting effect of the electrode using the composite foil.

[0029] (4) The composite foil of the present invention is more convenient to weld, which can improve production efficiency, and the composite foil can be welded using conventional ultrasonic spot welding equipment, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a top view of the composite foil of the present invention.

[0031] Figure 2 It is a front view of the composite foil of the present invention.

[0032] Among them, 1-base film, 2-metal layer, 3-first metal mesh, 4-second metal mesh. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the implementation methods are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0034] In a first specific embodiment, the present invention provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a base film and metal layers on both sides of the base film.

[0035] A first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side. The first metal mesh and the second metal mesh are connected at the side of the composite layer.

[0036] The composite foil material further includes a first metal fixing film, which covers the first metal mesh and contacts the composite layer in the mesh holes of the first metal mesh, so that the composite layer is fixed to the first metal mesh.

[0037] The composite foil further includes a second metal fixing film, which covers the second metal mesh and contacts the composite layer in the mesh holes of the second metal mesh, so that the composite layer is fixed to the second metal mesh.

[0038] The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

[0039] Since the traditional composite foil only includes a base film and metal layers on both sides of the base film, the electrical conductivity, thermal conductivity and peeling strength of the foil are low, and there is no conduction between the layers. The composite foil provided by the present invention is provided with metal meshes on both sides of the composite layer composed of the base film and the metal layer. The provision of the metal meshes can not only improve the electrical conductivity and thermal conductivity of the traditional composite foil, but the texture of the metal meshes can also help to retain more slurry during coating, thereby facilitating the preparation of thick electrodes. At the same time, under the condition of the same active material loading, the peeling force between the active material layer and the composite foil can also be improved; the provision of the metal meshes can also improve the porosity of the electrode plate, thereby improving the electrolyte infiltration effect of the electrode plate.

[0040] Furthermore, the side of the composite layer of the present invention is also provided with a metal mesh, and the metal meshes on the side are also connected, so as to realize the overall conduction of the composite foil. In addition, the surface of the metal mesh and the surface of the composite layer in the metal mesh of the present invention are provided with a metal fixing film, and the metal fixing film fixes the composite layer and the metal mesh together, so that the composite layer and the metal mesh become a solid whole.

[0041] It should be noted that after the first metal fixing film and the second metal fixing film are set, the surface of the composite foil still has the mesh texture of the first metal mesh and the second metal mesh, that is, after the first metal fixing film and the second metal fixing film are set, the metal mesh is not smoothed into a flat layered structure, thereby ensuring that the metal mesh can play its role.

[0042] The top view of the composite foil of the present invention is as follows Figure 1 As shown, the front view is as Figure 2 As shown, metal layers 2 are arranged on both sides of the base film 1, and first metal meshes 3 and second metal meshes 4 are arranged on both sides of the metal layer 2. A metal mesh is also arranged on the side of the composite layer formed by the base film 1 and the metal layer 2, and the first metal mesh 3 and the second metal mesh 4 on the side are connected together. At the same time, a metal fixing film is arranged on the outside of the metal mesh to fix the metal mesh and the composite layer into a whole.

[0043] In some embodiments, the thickness of the first metal fixed film is smaller than the thickness of the first metal mesh, and the thickness of the second metal fixed film is smaller than the thickness of the second metal mesh.

[0044] The metal fixing film of the present invention is preferably thinner than the thickness of the metal mesh, that is, a metal fixing film thinner than the metal mesh can better ensure the mesh texture of the metal mesh.

[0045] In some embodiments, the thickness of the first metal fixed film is 5%-10% of the thickness of the first metal mesh, for example, it can be 5%, 6%, 7%, 8%, 9% or 10%, and the thickness of the second metal fixed film is 5%-10% of the thickness of the second metal mesh, for example, it can be 5%, 6%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The thickness of the metal fixing film of the present invention is preferably 5-10% of the thickness of the metal mesh, so that the metal fixing film can not only play the role of fixing the metal mesh, but also maintain the mesh texture of the metal mesh on the surface of the composite foil.

[0047] In some embodiments, the thickness of the first metal mesh and the second metal mesh are independently 3 μm-5 μm, for example, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In some embodiments, the mesh size of the first metal mesh and the second metal mesh is 50-120 mesh, for example, it can be 50 mesh, 60 mesh, 80 mesh, 100 mesh or 120 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] In some embodiments, the first metal mesh and the second metal mesh are independently copper mesh or aluminum mesh, and the metal material of the first metal mesh and the second metal mesh is the same as the metal material of the metal layer, that is, if the metal layer in the composite layer of the present invention is a copper layer, the first metal mesh and the second metal mesh are copper mesh, and if it is an aluminum layer, the first metal mesh and the second metal mesh are aluminum mesh.

[0050] In some embodiments, the first metal fixed film and the second metal fixed film are independently copper films or aluminum films.

[0051] In some embodiments, the base film includes a polymer film layer, and the metal layer includes a copper layer or an aluminum layer.

[0052] Exemplarily, when the metal layer is a copper layer, the first metal mesh and the second metal mesh are both copper meshes, and the first metal fixed film and the second metal fixed film are both copper films; when the metal layer is an aluminum layer, the first metal mesh and the second metal mesh are both aluminum meshes, and the first metal fixed film and the second metal fixed film are both aluminum films.

[0053] In some embodiments, the polymer film layer includes a PET (polyethylene terephthalate) film layer, a PP (polypropylene) film layer, or a composite film layer of PET and PP.

[0054] Exemplarily, the thickness of the base film is 3-12 μm, for example, 3 μm, 4.5 μm, 6 μm, 8 μm, or 12 μm, and the thickness of the metal layer is 1-2 μm, for example, 1 μm, 1.5 μm or 2 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In a second specific embodiment, a method for preparing the composite foil as described in the first specific embodiment is provided, and the preparation method comprises the following steps:

[0056] The first metal mesh is arranged on one side of the composite layer, and the second metal mesh is arranged on the other side of the composite layer, and then hot pressing is performed.

[0057] After hot pressing, a first metal fixing film is arranged on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixing film is arranged on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh.

[0058] Finally, the first metal mesh and the second metal mesh on the side of the composite layer are connected to obtain the composite foil.

[0059] The present invention first arranges the first metal mesh and the second metal mesh on one side and the other side of the composite layer, then performs hot pressing to load the first metal mesh and the second metal mesh on the surface and side of the composite layer, then arranges the first metal fixing film and the second metal fixing film to fix the metal mesh and the composite layer, and finally connects the first metal mesh and the second metal mesh on the side of the composite layer.

[0060] The first metal mesh and the second metal mesh of the present invention are wider than the width of the composite layer, so that the first metal mesh and the second metal mesh can be arranged on the surface and the side of the composite layer, and can also be connected together. The present invention does not specifically limit the width of the first metal mesh and the second metal mesh wider than the composite layer. Those skilled in the art can make a reasonable choice based on the thickness of the composite layer and the need to connect the side metal meshes together; illustratively, the first metal mesh and the second metal mesh are independently 3-5 cm wider than the single side width of the composite layer, for example, can be 3 cm, 4 cm or 5 cm, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0061] In addition, the present invention only needs to ensure that the first metal mesh and the second metal mesh are wider than the width of the composite layer. Since the composite foil material of the present invention can be cut according to the actual application size, the cutting process can be carried out according to the size of the composite foil material. Figure 2 The front view of the composite foil is cut to ensure that the front view of the composite foil obtained after cutting is consistent with Figure 2 same.

[0062] It should be noted that the side surface of the composite layer in the present invention refers to the side surface in the width direction of the composite layer.

[0063] In some embodiments, the hot pressing temperature is 400°C-500°C, for example, 400°C, 450°C or 500°C, the pressure is 0.5MPa-1MPa, for example, 0.5MPa, 0.7MPa, 0.9MPa or 1MPa, and the time is 10s-50s, for example, 10s, 20s, 30s, 40s or 50s, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] In some embodiments, the methods of providing the first metal fixed film and the second metal fixed film respectively and independently include magnetron sputtering or vacuum evaporation.

[0065] The present invention can use magnetron sputtering or vacuum evaporation to set the metal fixed film, so that the metal mesh and the composite layer become a whole; in addition, the present invention does not specifically limit the specific conditions for setting the first metal fixed film and the second metal fixed film by magnetron sputtering and vacuum evaporation, as long as a metal fixed film of the target thickness can be obtained.

[0066] In some embodiments, the method of connecting the first metal mesh and the second metal mesh on the side of the composite layer includes welding. For example, conventional ultrasonic spot welding equipment can be used to weld the composite foil.

[0067] The present invention further arranges a metal mesh on the side of the composite layer, so the metal mesh on the side of the composite layer can be welded, making the welding of the composite foil more convenient and the production efficiency higher.

[0068] In some embodiments, the method for preparing the composite layer includes: setting a metal layer on both sides of the base film by magnetron sputtering or vacuum evaporation. The present invention does not specifically limit the specific conditions for setting the metal layer by magnetron sputtering and vacuum evaporation, as long as a metal layer of the target thickness can be obtained.

[0069] The technical solution of the present invention is further illustrated by specific embodiments below.

[0070] Example 1

[0071] This embodiment provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a PET layer with a thickness of 3 μm and copper layers with a thickness of 1 μm on both sides of the PET layer.

[0072] A first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side. The first metal mesh and the second metal mesh are connected at the side of the composite layer, and both the first metal mesh and the second metal mesh are copper meshes with a thickness of 3 μm.

[0073] The composite foil also includes a first metal fixing film with a thickness of 10% of the thickness of the first metal mesh, the first metal fixing film covers the first metal mesh and contacts the composite layer in the mesh holes of the first metal mesh, so that the composite layer is fixed to the first metal mesh; the composite foil also includes a second metal fixing film with a thickness of 10% of the thickness of the second metal mesh, the second metal fixing film covers the second metal mesh and contacts the composite layer in the mesh holes of the second metal mesh, so that the composite layer is fixed to the second metal mesh; the first metal fixing film and the second metal fixing film are copper films.

[0074] The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

[0075] The preparation method of the composite foil comprises the following steps:

[0076] Copper layers were prepared on both sides of the PET layer by magnetron sputtering to obtain a composite layer. A first metal mesh was set on one side of the composite layer, and the width of the first metal mesh was 3 cm wider than the width of the composite layer on each side, with a total width of 6 cm. A second metal mesh was set on the other side of the composite layer, and the width of the second metal mesh was 3 cm wider than the width of the composite layer on each side, with a total width of 6 cm. Then, hot pressing was performed at 450°C and 0.7 MPa for 30 seconds.

[0077] After hot pressing, copper is magnetron sputtered to obtain a first metal fixed film on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixed film is obtained on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh. Finally, the first metal mesh and the second metal mesh on the side of the composite layer are welded by ultrasonic spot welding to obtain the composite foil.

[0078] Example 2

[0079] This embodiment provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a PET layer with a thickness of 3 μm and copper layers with a thickness of 1 μm on both sides of the PET layer.

[0080] A first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side. The first metal mesh and the second metal mesh are connected at the side of the composite layer, and both the first metal mesh and the second metal mesh are copper meshes with a thickness of 3 μm.

[0081] The composite foil also includes a first metal fixing film with a thickness of 5% of the thickness of the first metal mesh, the first metal fixing film covers the first metal mesh and contacts the composite layer in the mesh holes of the first metal mesh, so that the composite layer is fixed to the first metal mesh; the composite foil also includes a second metal fixing film with a thickness of 5% of the thickness of the second metal mesh, the second metal fixing film covers the second metal mesh and contacts the composite layer in the mesh holes of the second metal mesh, so that the composite layer is fixed to the second metal mesh; the first metal fixing film and the second metal fixing film are copper films.

[0082] The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

[0083] The preparation method of the composite foil comprises the following steps:

[0084] Copper layers were prepared on both sides of the PET layer by magnetron sputtering to obtain a composite layer. A first metal mesh was arranged on one side of the composite layer, and the width of the first metal mesh was 4 cm wider than the width of the composite layer on each side, with a total width of 8 cm. A second metal mesh was arranged on the other side of the composite layer, and the width of the second metal mesh was 4 cm wider than the width of the composite layer on each side, with a total width of 8 cm. Then, hot pressing was performed at 500°C and 0.5 MPa for 50 seconds.

[0085] After hot pressing, copper is magnetron sputtered to obtain a first metal fixed film on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixed film is obtained on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh. Finally, the first metal mesh and the second metal mesh on the side of the composite layer are welded by ultrasonic spot welding to obtain the composite foil.

[0086] Example 3

[0087] This embodiment provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a PET layer with a thickness of 4 μm and copper layers with a thickness of 1.5 μm on both sides of the PET layer.

[0088] A first metal mesh is arranged on the surface and side of one side of the composite layer, and a second metal mesh is arranged on the surface and side of the other side. The first metal mesh and the second metal mesh are connected at the side of the composite layer, and both the first metal mesh and the second metal mesh are copper meshes with a thickness of 5 μm.

[0089] The composite foil also includes a first metal fixing film with a thickness of 10% of the thickness of the first metal mesh, the first metal fixing film covers the first metal mesh and contacts the composite layer in the mesh holes of the first metal mesh, so that the composite layer is fixed to the first metal mesh; the composite foil also includes a second metal fixing film with a thickness of 10% of the thickness of the second metal mesh, the second metal fixing film covers the second metal mesh and contacts the composite layer in the mesh holes of the second metal mesh, so that the composite layer is fixed to the second metal mesh; the first metal fixing film and the second metal fixing film are copper films.

[0090] The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

[0091] The preparation method of the composite foil comprises the following steps:

[0092] Copper layers were prepared on both sides of the PET layer by magnetron sputtering to obtain a composite layer. A first metal mesh was arranged on one side of the composite layer, and the width of the first metal mesh was 5 cm wider than the width of the composite layer on each side, with a total width of 10 cm. A second metal mesh was arranged on the other side of the composite layer, and the width of the second metal mesh was 5 cm wider than the width of the composite layer on each side, with a total width of 10 cm. Then, hot pressing was performed at 400°C and 1 MPa for 10 s.

[0093] After hot pressing, copper is magnetron sputtered to obtain a first metal fixed film on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixed film is obtained on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh. Finally, the first metal mesh and the second metal mesh on the side of the composite layer are welded by ultrasonic spot welding to obtain the composite foil.

[0094] Example 4

[0095] This embodiment provides a composite foil, which is the same as that of Embodiment 1 except that the thickness of the first metal fixing film is 3% of the thickness of the first metal mesh, and the thickness of the second metal fixing film is 3% of the thickness of the second metal mesh.

[0096] Example 5

[0097] This embodiment provides a composite foil, which is the same as Embodiment 1 except that the thickness of the first metal fixing film is 20% of the thickness of the first metal mesh, and the thickness of the second metal fixing film is 20% of the thickness of the second metal mesh.

[0098] Comparative Example 1

[0099] This comparative example provides a composite foil material, wherein the composite foil material comprises a composite layer, wherein the composite layer comprises a PET layer with a thickness of 3 μm and copper layers with a thickness of 1 μm on both sides of the PET layer.

[0100] The preparation method of the composite foil comprises the following steps:

[0101] The copper layers are prepared on both sides of the PET layer by a magnetron sputtering method to obtain the composite foil.

[0102] Comparative Example 2

[0103] This comparative example provides a composite foil, which includes a composite layer, and the composite layer includes a PET layer with a thickness of 3 μm and a copper layer with a thickness of 4.3 μm on both sides of the PET layer, that is, the composite foil in this comparative example replaces the first metal mesh, the second metal mesh, the first metal fixed film and the second metal fixed film in Example 1 with copper layers of equal thickness.

[0104] The preparation method of the composite foil comprises the following steps:

[0105] The copper layers are prepared on both sides of the PET layer by a magnetron sputtering method to obtain the composite foil.

[0106] Comparative Example 3

[0107] This comparative example provides a composite foil, which is the same as Example 1 except that the composite foil does not include the first metal fixing film and the second metal fixing film.

[0108] The preparation method of the composite foil is the same as that of Example 1 except that magnetron sputtering of copper is not performed after hot pressing.

[0109] The surfaces of both sides of the composite foil obtained in the above embodiments and comparative examples were coated with electrode slurry, and then dried and rolled to obtain electrode plates, wherein the electrode slurry included 97wt% of NMC ternary, 1wt% of SP, and 2wt% of PVDF; the obtained electrode plates were subjected to a peel strength performance test, and the test method was to use a 19mm wide 3M tape to stick the plate for 10-15cm, and test vertically on an adhesion tester, the control scheme selected peeling, the control value was 500mm / min, the switching condition was deformation, and the test results are shown in Table 1:

[0110] Table 1

[0111]

[0112] From Table 1 we can see that:

[0113] It can be seen from Examples 1-3 and Comparative Example 1 that the metal mesh of the present invention and the metal fixing film matched with the metal mesh can significantly improve the peeling performance of the electrode piece, and since the entire composite foil of the present invention is a whole, a copper mesh is also provided on the side of the composite layer, so that the layers in the composite layer can be mutually conductive; it can be seen from Example 1 and Comparative Example 2 that after the thickness of the metal mesh and the metal fixing film is replaced with a copper layer, the effect of Example 1 cannot be achieved; it can be seen from Example 1 and Comparative Example 3 that the metal fixing film of the present invention can fix the metal mesh and the composite layer, and improve the peeling performance of the electrode piece; it can be seen from Examples 1 and 4-5 that the thickness of the metal fixing film will affect its fixing effect and the mesh texture of the metal mesh. The present invention preferably satisfies a specific relationship between the thickness of the metal fixing film and the metal mesh, which can further improve the peeling performance of the electrode piece.

[0114] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A composite foil, characterized in that: The composite foil material comprises a composite layer, and the composite layer comprises a base film and metal layers on both sides of the base film; A first metal mesh is disposed on the surface and side of one side of the composite layer, and a second metal mesh is disposed on the surface and side of the other side, wherein the first metal mesh and the second metal mesh are connected at the side of the composite layer; The composite foil further includes a first metal fixing film, which covers the first metal mesh and contacts the composite layer in the mesh of the first metal mesh, so that the composite layer is fixed to the first metal mesh; The composite foil further includes a second metal fixing film, which covers the second metal mesh and contacts the composite layer in the mesh of the second metal mesh, so that the composite layer is fixed to the second metal mesh; The surface of the composite foil material has mesh patterns of a first metal mesh and a second metal mesh.

2. The composite foil according to claim 1, characterized in that: The thickness of the first metal fixing film is smaller than the thickness of the first metal mesh, and the thickness of the second metal fixing film is smaller than the thickness of the second metal mesh.

3. The composite foil according to claim 2, characterized in that: The thickness of the first metal fixed film is 5%-10% of the thickness of the first metal mesh, and the thickness of the second metal fixed film is 5%-10% of the thickness of the second metal mesh; The thickness of the first metal mesh and the second metal mesh are independently 3 μm-5 μm.

4. The composite foil according to any one of claims 1 to 3, characterized in that: The first metal mesh and the second metal mesh are independently copper mesh or aluminum mesh, and the metal material of the first metal mesh and the second metal mesh is the same as the metal material of the metal layer.

5. The composite foil according to any one of claims 1 to 3, characterized in that: The first metal fixed film and the second metal fixed film are independently copper films or aluminum films; The base film includes a polymer film layer, and the metal layer includes a copper layer or an aluminum layer.

6. A method for preparing the composite foil according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: The first metal mesh is arranged on one side of the composite layer, and the second metal mesh is arranged on the other side of the composite layer, and then hot pressing is performed; After hot pressing, a first metal fixing film is arranged on the surface of the first metal mesh and the surface of the composite layer in the first metal mesh, and a second metal fixing film is arranged on the surface of the second metal mesh and the surface of the composite layer in the second metal mesh; Finally, the first metal mesh and the second metal mesh on the side of the composite layer are connected to obtain the composite foil.

7. The preparation method according to claim 6, characterized in that: The methods of providing the first metal fixed film and the second metal fixed film include magnetron sputtering or vacuum evaporation respectively and independently.

8. The preparation method according to claim 6 or 7, characterized in that: The method of connecting the first metal mesh and the second metal mesh on the side of the composite layer includes welding.

9. An electrode plate, characterized in that: The electrode plate comprises the composite foil material as described in any one of claims 1-5.

10. A battery, characterized in that: The battery comprises the composite foil material according to any one of claims 1 to 5, or the electrode plate according to claim 9.

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