Composite conductive film

Abstract

The invention provides a composite conductive film which comprises a supporting layer, a metal layer is arranged on the supporting layer, and when XRD is adopted to characterize the metal layer, the crystal face orientation and content of the metal layer are consistent with the crystal face orientation and content of metal contained in the metal layer. According to the scheme, the crystal face orientation and content of the metal layer are consistent with the crystal face orientation and content of the metal of the metal layer, so that the metal layer of the composite current collector is higher in purity, the purity is higher, the conductivity is better, the composite conductive film has higher conductivity, and the service life of the composite conductive film is prolonged. The higher the electric conductivity is, the less the metal used for reaching the target electric conductivity is, the lower the thickness is, the lower the weight and the cost are, and the more competitive power is.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a composite conductive film. Background Art

[0002] The composite conductive film has both conductive functions and flexible characteristics, making it widely used. The structure of the composite conductive film is an intermediate support layer, and coating materials that can conduct electricity are provided on two surfaces in the thickness direction of the support layer. However, the coating materials on the existing composite conductive films have a relatively large resistivity and a relatively large weight, resulting in a relatively high cost.

[0003] Therefore, the existing technology still needs to be improved. Summary of the Invention

[0004] In view of the deficiencies of the above-mentioned existing technology, the purpose of the present invention is to provide a composite conductive film to solve the problem that the coating materials on the existing composite conductive films in the background art have a relatively large resistivity and a relatively large weight, resulting in a relatively high cost.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A composite conductive film includes a support layer, and a metal layer is provided on the support layer. When the metal layer is characterized by XRD, the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal in the metal layer.

[0006] Through the above solution, since the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal contained in the metal layer of the composite current collector of the present invention, the metal layer of the composite current collector of the present invention has a higher purity. The higher the purity, the better the conductivity. Therefore, the composite conductive film of the present invention has a higher conductivity. The higher the conductivity, the less metal is used to reach the target conductivity, and the lower the thickness. Then, the weight and cost are less, making it more competitive.

[0007] In the present invention, when the metal layer is characterized by XRD, diffraction peaks appear at 30° - 40°, 40° - 50°, 60° - 70° and 70° - 80°.

[0008] In the present invention, the height of the diffraction peak at 30° - 40° is greater than the height of the diffraction peak at 40° - 50°.

[0009] In the present invention, the height of the diffraction peak at 40° - 50° is greater than the height of the diffraction peak at 30° - 40°.

[0010] In the present invention, the height of the diffraction peak at 60° - 70° is less than the height of the diffraction peak at 30° - 40°.

[0011] In the present invention, the height of the diffraction peak located at 70°-80° is less than the height of the diffraction peak located at 30°-40°.

[0012] In the present invention, the height of the diffraction peak located at 70°-80° is less than or equal to the height of the diffraction peak located at 60°-70°.

[0013] In the present invention, the height of the diffraction peak located at 40°-50° is 1-3 times the height of the diffraction peak located at 30°-40°.

[0014] In the present invention, the height of the diffraction peak located at 30°-40° is 1-3 times the height of the diffraction peak located at 40°-50°.

[0015] In the present invention, the height of the diffraction peak located at 60°-70° is 1-1.5 times the height of the diffraction peak located at 70°-80°.

[0016] Compared with the prior art, the present invention provides a composite conductive film. Since the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal contained in the metal layer, the metal layer of the composite current collector of the present invention has a higher purity, and the higher the purity, the better the electrical conductivity, so that the composite conductive film of the present invention has a higher conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a composite conductive film according to an embodiment of the present application; Figure 2 It is an XRD diagram of the composite conductive film provided by the present invention; Figure 3 It is another XRD diagram of the composite conductive film provided by the present invention; Figure 4 It is a schematic structural diagram of a composite conductive film according to another embodiment of the present application.

[0018] In the figure: 1. Support layer, 2. Metal layer, 3. First coating, 4. Second coating. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the purpose, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and examples. 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.

[0020] It should be noted that when a component is referred to as "mounted on", "fixed to" or "disposed on" another component, it can be directly on the other component or there may be an intermediate component at the same time. When a component is referred to as "connected to" another component, it can be directly connected to the other component or there may be an intermediate component at the same time.

[0021] It should also be noted that the orientation terms such as left, right, up, and down in the embodiments of the present invention are only relative concepts to each other or are referenced based on the normal use state of the product, and should not be considered restrictive.

[0022] The function of the conductive film is to conduct electricity, that is, to allow current to pass through the surface of the conductive film. Its conductive function mainly comes from the conductive coating on the surface of the conductive film. However, the current collecting ability of the conductive coating on the surface of the current composite conductive film is weak. Therefore, as Figure 1 shown, the inventor proposes a composite conductive film, including a support layer 1, and a metal layer 2 is provided on the support layer. When the metal layer is characterized by XRD, the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal contained in the metal layer. Since the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal contained in the metal layer, in the composite conductive film of the invention, the composition of the metal layer is single and there are no other impurities, thus ensuring the conductive performance of the metal layer.

[0023] Furthermore, in the composite conductive film of the present invention, when the composite conductive film is characterized by XRD for the metal layer, as Figure 2As shown, diffraction peaks appear at 30°-40°, 40°-50°, 60°-70° and 70°-80°. Since the above diffraction peaks appear at 30°-40°, 40°-50°, 60°-70° and 70°-80°, the composite conductive film of the present invention has high conductivity while also having better corrosion resistance and mechanical properties. This is because when the diffraction peak is at 30°-40°, the crystal plane index of the crystal contained in the metal layer is 111, and the surface energy of the crystal with the crystal plane index of 111 is low, which makes the metal layer relatively compact and improves the conductivity of the composite conductive film of the present invention; when the diffraction peak appears at 40°-50°, the crystal plane index of the crystal structure of the metal layer is 200, and the shape of the crystal with the crystal plane index of 200 is a square plane, with four atoms arranged on each face, that is, the atoms of the crystal with the crystal plane index of 200 are arranged relatively sparsely. In this way, the crystals with the crystal plane index of 111 and 200 are embedded and cooperate with each other to improve the conductivity and bonding force of the metal layer. When the diffraction peak appears at 60°-70°, the crystal plane index of the metal crystal of the metal layer is 220, and the crystal with the crystal plane index of 220 can significantly slow down the penetration of the corrosive medium and improve the corrosion resistance of the composite conductive film of the present invention. When the diffraction peak appears at 70°-80°, the crystal plane index of the metal crystal of the metal layer is 311, and the crystal structure with the crystal plane index of 311 is a rhombic prism surface and is sensitive to defects. Thus, if the composite aluminum conductive film is characterized by XRD for the metal layer, if the peak with the crystal plane index of 311 is abnormally enhanced, it may indicate the presence of impurity phases or an increase in the defect density in the sample, that is, the crystal with the crystal plane index of 311 acts as a probe and can always know the defects of the composite conductive film.

[0024] Furthermore, in the composite conductive film of the present invention, the material of the support layer 1 can be one or more of polyoxymethylene, polyethylene, polyvinyl methyl ether, polyvinyl ethyl ether, ethylene-propylene copolymer, polyvinyl alcohol, polyvinyl acetate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyacrylic acid, polymethyl methacrylate, polyethyl acrylate, poly(butyl α-cyanoacrylate), polyacrylonitrile, polyisobutylene rubber, chloroprene rubber, natural rubber, gutta-percha, styrene-butadiene rubber, polydecamethylene formamide, polyhexamethylene adipamide, polydecamethylene adipamide, polyethylene terephthalate, polyethylene oxide, polyphenylene sulfide, poly[bis(trifluoroethoxy)phosphazene], polydimethylsiloxane, biaxially oriented polypropylene film. In the present invention, the height of the diffraction peak at 30°-40° is greater than the height of the diffraction peak at 40°-50°. When the diffraction peak is at 30°-40°, the crystal plane index of the metal layer is 111, and when the diffraction peak appears at 40°-50°, the crystal plane index of the metal layer crystal is 200. Thus, since the content of the crystal with the crystal plane index of 111 is greater than the content of the crystal with the crystal plane index of 200, the composite conductive film of the invention has better electrical conductivity, better thermal conductivity and higher metal layer adhesion while having greater electrical conductivity. The better electrical conductivity is because the atoms of the crystal with the crystal plane index of 111 are more dense, and the better thermal conductivity is because the distance between the crystal planes of the crystal with the crystal plane index of 111 is shorter and more ordered, which also promotes phonon conduction and is conducive to heat transfer. The better metal layer adhesion is because the atoms of the crystal with the crystal plane index of 111 are small and closely arranged, while the atoms of the crystal with the crystal plane index of 200 are large and loose. Thus, the small and closely arranged 111 crystal will interact with the large and loose crystal with the crystal plane index of 200, jointly making the coating adhesion on the composite conductive film of the present invention higher and having greater tensile strength. Further, this embodiment also provides a preparation method of the above composite conductive film, including the following steps: Step S1, unwind the support layer and place it in a vacuum evaporation device; Step S2, form a metal coating on the support layer by means of roll coating. The film running speed of the support layer in the vacuum evaporation device is 18 m / min, and the main roller temperature of the vacuum evaporation device is -5 / -15 °C. In this way, a composite conductive film with better electrical conductivity and higher metal layer adhesion can be obtained.

[0025] Further, in the composite conductive film of the present invention, when the metal layer is characterized by XRD, the height of the diffraction peak at 60°-70° is greater than the height of the diffraction peak at 30°-40°. Since the crystal plane index of the crystal with the diffraction peak at 60°-70° is 220, and the atomic arrangement with the crystal plane index of 220 is the most dense, and its crystal plane spacing d220 is approximately equal to 0.142 nm, and the dislocation slip resistance is greater. That is to say, when the diffraction peak with the crystal plane index of 220 is greater than the diffraction peak with the crystal plane index of 111, the tensile strength of the composite conductive film is greater. Moreover, the short-range order of the 111 crystal plane promotes phonon conduction, which is beneficial to improving the thermal conductivity of the composite conductive film shown in this embodiment. And the 220 crystal plane is densely arranged, and the high crystal plane density can inhibit crack propagation and improve the fatigue resistance of the shown composite conductive film.

[0026] Further, in the composite conductive film of the present invention, as Figure 3 shown, the height of the diffraction peak at 40°-50° is greater than the height of the diffraction peak at 30°-40°. When the metal layer is characterized by XRD, since the crystal plane index of the crystal with the diffraction peak at 40°-50° is 200, and the crystal with the crystal plane coefficient of 200 is relatively sparse, and the sparse crystal plane is more likely to form micro-nano structures during the preparation process, resulting in an increase in surface roughness (Ra). The increase in roughness can significantly improve the adhesion of the subsequent coating. In this embodiment, as Figure 4 shown, the composite conductive film includes a first coating 3 and a second coating 4. In the first coating 3, the height of the diffraction peak at 40°-50° is greater than the height of the diffraction peak at 30°-40°. Then, the second coating 4 is formed on the first coating 3. Since the height of the diffraction peak at 40°-50° is greater than the height of the diffraction peak at 30°-40°, the second coating 4 is not easily detached from the first coating 3. In this embodiment, the composite conductive film can be prepared as follows: Step S1: Use a vacuum evaporation device to form the first coating 3 on the support layer; Step S2: Use XRD to detect the support layer 1 with the first coating 3 formed thereon; Step S3: Use a vacuum evaporation device to form the second coating 4 on the first coating 3. In this embodiment, in the second coating 4, the height of the diffraction peak at 30°-40° is greater than the height of the diffraction peak at 40°-50°. That is to say, in the second coating 4, the content of the crystal with the crystal plane index of 111 is greater than the content of the crystal with the crystal plane index of 200. In this way, the crystal with the crystal plane index of 111 in the second coating 4 will fill the space between the crystals with the crystal plane index of 200 in the first coating 3, so that the crystals with the crystal plane index of 111 and the crystals with the crystal plane index of 200 are more closely combined, and together they can improve the adhesion between the first coating 3 and the second coating 4.

[0027] Further, in the composite conductive film of the present invention, as Figure 3 shown, the height of the diffraction peak located at 60°-70° is less than the height of the diffraction peak located at 30°-40°. When the metal layer is characterized by XRD, since the crystal plane index of the crystal with the diffraction peak located at 60°-70° is 220, and when the diffraction peak is at 30°-40°, the crystal structure arrangement of the metal layer has a crystal plane index of 111. That is to say, in this embodiment, in the metal layer, the crystal content with the crystal plane index of 220 is less than the crystal content with the crystal plane index of 111. In this way, because the crystal atoms with the crystal plane index of 220 are closely arranged and have a relatively high surface state density, it can enhance electron scattering, resulting in a slight increase in resistivity. A slightly increased resistance can make the composite conductive film of the present invention more secure. The higher the resistivity, the greater the current density, and the more likely it is to generate heat. And the crystal with the crystal plane index of 220 can play a role in adjusting the resistance of the composite conductive film of the present invention. In this embodiment, the preparation method of the composite conductive film may include the following steps: Step S1, first take a support layer; Step S2, adjust the parameters of the evaporation coating equipment to form a metal coating on the support layer. The parameters of the evaporation equipment are as follows: set the vacuum degree in the vacuum chamber of the vacuum evaporation to 0.000023 mbar, and let the support layer be coated under the condition of a vacuum degree of 0.000023 mbar; pass a current of 40 A - 65 A into the evaporation source in the evaporation equipment; adjust the temperature of the main cooling roller in the evaporation equipment to be between -5° and -15°; adjust the film running speed of the support layer to be 10 m / min - 20 m / min; after coating the support layer, control the winding temperature of the support layer during winding to be 15° - 21°. Through the above steps and parameters, the composite conductive film of this embodiment can be obtained.

[0028] Further, in the composite conductive film of the present invention, as Figure 2 and 3 shown, the height of the diffraction peak located at 70°-80° is less than the height of the diffraction peak located at 30°-40°. When the metal layer is characterized by XRD, the appearance of the diffraction peak at 70°-80° represents that the crystal plane index of the metal layer crystal is 311, and the appearance of the diffraction peak at 30°-40° represents that the metal crystal plane index of the metal layer is 111. Since the crystal with the crystal plane index of 311 mainly plays the role of a probe, the crystal with the crystal plane index of 311 should be as small as possible, so as to reduce the mass of the composite conductive film, reduce costs, and improve the conductive performance.

[0029] Further, in the composite conductive film of the present invention, when the metal layer is characterized by XRD, diffraction peaks appear at 70°-80°, representing that the metal crystal plane index of the metal layer is 311, and diffraction peaks appear at 60°-70°, representing that the metal crystal plane index of the metal layer is 220. In this embodiment, as Figure 2 shown, the height of the diffraction peak located at 70°-80° is less than or equal to the height of the diffraction peak located at 60°-70°. Since the 311 crystal plane is an orthorhombic prism plane, its atomic arrangement is relatively loose and the grain boundary resistance is large, making the tensile strength of the composite conductive film of the present invention higher. However, grain boundaries and defects lead to an increase in electron scattering and a decrease in conductivity. The 220 crystal plane has a high surface state density due to the close atomic arrangement, which enhances electron scattering and leads to an increase in resistivity. In this way, by adjusting the contents of the 220 crystal plane and the 311 crystal plane, the composite conductive film of this embodiment can make the composite conductive film of the present invention have a low resistivity while improving the tensile strength of the composite conductive film.

[0030] Further, in the composite conductive film of the present invention, as Figure 2As shown, the height of the diffraction peak at 30°-40° is 1-3 times the height of the diffraction peak at 40°-50°. When the metal layer is characterized by XRD, the diffraction peak appears at 40°-50°, indicating that the metal crystal plane index of the metal layer is 200, and the diffraction peak appears at 30°-40°, indicating that the metal crystal plane index of the metal layer is 111. In this embodiment, the height of the diffraction peak at 30°-40° is 1-3 times the height of the diffraction peak at 40°-50°. Such a setting can significantly improve the elongation and tensile strength of the composite conductive film in this embodiment. This is because the close packing of the crystal with a crystal plane index of 111 can promote dislocation slip, thereby increasing the elongation. The crystal with a crystal plane index of 200 has a cubic crystal plane, and its grain boundary resistance inhibits dislocation movement, which can increase the tensile strength. Such a ratio can also neutralize the problem of the decrease in corrosion resistance caused by the crystal with a crystal plane index of 200, because the crystal with a crystal plane index of 111 can form a dense oxide film, enhancing the corrosion resistance of the composite conductive film of the present invention. In this embodiment, the preparation method of the composite conductive film may include the following steps: Step S1, first take a support layer; Step S2, adjust the parameters of the evaporation coating equipment to form a metal coating on the support layer. The parameters of the evaporation equipment are as follows: set the vacuum degree in the vacuum chamber of the vacuum evaporation to 0.000023 mbar, and let the support layer be coated under the condition of a vacuum degree of 0.000023 mbar. Pass a current of 40 A-65 A into the evaporation source in the evaporation equipment, adjust the temperature of the main cooling roller in the evaporation equipment to be between -5° and -15°, adjust the film running speed of the support layer to be 10 m / min-20 m / min. After coating the support layer, control the winding temperature of the support layer during winding to be 17°-18°. Through the above steps and parameters, the composite conductive film of this embodiment can be obtained.

[0031] Further, in the composite conductive film of the present invention, as Figure 2As shown, when the metal layer is characterized by XRD, the crystal plane index of the crystal with diffraction peaks appearing at 60° - 70° is 220, and the diffraction peaks appearing at 70° - 80° represent that the metal crystal plane index of the metal layer is 311. In the present invention, the height of the diffraction peak at 60° - 70° is 1 - 1.5 times the height of the diffraction peak at 70° - 80°. Thus, since the 311 crystal plane is a rhombic prism plane with relatively loose atomic arrangement and large grain boundary resistance, it will increase the tensile strength of the composite conductive film of the present invention, making the composite conductive film of the present invention have greater puncture resistance. However, too many metal crystals with a crystal plane index of 311 will lead to a decrease in ductility. In the composite conductive film of the present invention, the crystal with a crystal plane index of 220 is 1 - 1.5 times the height of the diffraction peak of the crystal with a 311 crystal plane, making the composite conductive film of the present invention not only have high puncture resistance, but also can make up for the deficiency of elongation by controlling the content of the crystal with a crystal plane index of 220, and also have high conductivity.

[0032] In summary, the present invention provides a composite conductive film, including a support layer, and a metal layer is provided on the support layer. When the metal layer is characterized by XRD, the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal in the metal layer. Since the crystal plane orientation and content of the metal layer are consistent with the crystal plane orientation and content of the metal in the metal layer, the metal layer of the composite current collector of the present invention has higher purity, and the higher the purity, the better the conductivity, making the composite conductive film of the present invention have higher conductivity.

[0033] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solution and inventive concept of the present invention, and all such changes or substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A composite conductive film, characterized in that, It includes a support layer, and a metal layer is provided on the support layer. When the metal layer is characterized by XRD, the crystal plane orientation and content of the metal layer are consistent with those of the metal in the metal layer.

2. The composite conductive film according to claim 1, wherein When the metal layer is characterized by XRD, diffraction peaks appear at 30°-40°, 40°-50°, 60°-70° and 70°-80°.

3. The composite conductive film according to claim 2, wherein, The height of the diffraction peak at 30°-40° is greater than that of the diffraction peak at 40°-50°.

4. The composite conductive film according to claim 2, wherein The height of the diffraction peak at 40°-50° is greater than that of the diffraction peak at 30°-40°.

5. The composite conductive film according to claim 2, characterized in that, The height of the diffraction peak at 60°-70° is less than that of the diffraction peak at 30°-40°.

6. The composite conductive film according to claim 2, characterized in that, The height of the diffraction peak at 70°-80° is less than that of the diffraction peak at 30°-40°.

7. The composite conductive film according to claim 2, wherein The height of the diffraction peak at 70°-80° is less than or equal to that of the diffraction peak at 60°-70°.

8. The composite conductive film according to claim 4, wherein The height of the diffraction peak at 40°-50° is 1-3 times that of the diffraction peak at 30°-40°.

9. The composite conductive film according to claim 3, wherein The height of the diffraction peak at 30°-40° is 1-3 times that of the diffraction peak at 40°-50°.

10. The composite conductive film according to claim 2, characterized in that, The height of the diffraction peak at 60°-70° is 1-1.5 times that of the diffraction peak at 70°-80°.

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