Composite conductive film, preparation process and application thereof

Abstract

The object of the present invention is to disclose a composite conductive film, a preparation process and an application thereof, which comprises, from bottom to top, a first drum-plated layer, a first suspended-plated layer, a thin film carrier layer, a second suspended-plated layer and a second drum-plated layer, wherein the thickness of the thin film carrier layer is 2μm-50μm, the thickness of the first suspended-plated layer and the second suspended-plated layer are both 0.01μm-0.1μm, and the thickness of the first drum-plated layer and the second drum-plated layer are both 0.7μm-5μm; the composite conductive film preparation process comprises the following steps: arranging a first coating layer on the surface of the thin film carrier layer by a suspended coating machine; arranging a second coating layer on the surface of the first coating layer by a drum coating machine, and the beneficial effect of the present invention is that by successively arranging a suspended coating layer and a drum-plated coating layer on the surface of the thin film carrier layer, wherein the thickness of the suspended coating layer is 0.01μm-0.1μm, the suspended coating layer serves as a buffer layer, plays an anti-wrinkle role, and avoids wrinkles in the thin film carrier layer when the drum-plated coating layer is arranged, thereby eliminating empty plating lines.

Description

Technical Field

[0001] The present invention relates to the technical field of composite conductive films, and in particular to a composite conductive film, a preparation process and applications thereof. Background Art

[0002] Improving the energy density of batteries is one of the key measures to solve the problem of vehicle endurance. At present, people use thin films and copper or aluminum to prepare composite conductive foil to replace copper foil or aluminum foil current collectors, which can effectively reduce the weight of battery current collectors and increase their energy density. Composite conductive foil is copper or aluminum plated on the surface of the thin film. Vacuum coating has the advantages of strong coating bonding, uniform film layer and less pollution, and is increasingly valued. Vacuum coating equipment includes drum-type evaporation equipment and suspension evaporation equipment. Drum-type evaporation has the technical defects of easily causing wrinkles and empty lines on the substrate, while suspension evaporation has the technical defects of poor heat transfer and low deposition efficiency. A single vacuum coating equipment is difficult to meet actual needs in terms of preparation efficiency, cost, and yield rate.

[0003] In view of this, there is an urgent need to develop a composite conductive film, a preparation process and its application to overcome the above-mentioned defects. Summary of the invention

[0004] The purpose of the present invention is to disclose a composite conductive film, a preparation process and its application. By combining a suspension evaporation device and a drum evaporation device, a composite conductive film is prepared on the surface of a thin film carrier layer by suspension plating and drum plating in succession, taking into account preparation efficiency, cost and yield.

[0005] The first object of the present invention is to provide a composite conductive film.

[0006] The second object of the present invention is to provide a use of a composite conductive film.

[0007] The third object of the present invention is to provide a process for preparing a composite conductive film.

[0008] To achieve the above-mentioned first invention purpose, the present invention provides a composite conductive film, which includes, from bottom to top, a first drum-plated layer, a first suspended-plated layer, a thin film carrier layer, a second suspended-plated layer and a second drum-plated layer, the thin film carrier layer has a thickness of 2μm-50μm, the first suspended-plated layer and the second suspended-plated layer have a thickness of 0.01μm-0.1μm, and the first drum-plated layer and the second drum-plated layer have a thickness of 0.7μm-5μm.

[0009] To achieve the above-mentioned first invention purpose, the present invention also provides a composite conductive film, which includes, from bottom to top, a first drum-plated layer, a first suspended-plated layer, a thin film carrier layer, a second suspended-plated layer and a second drum-plated layer, the thickness of the thin film carrier layer is 4μm-10μm, the thickness of the first suspended-plated layer and the second suspended-plated layer are both 0.01μm-0.1μm, and the thickness of the first drum-plated layer and the second drum-plated layer are both 0.7μm-2μm.

[0010] Preferably, the film carrier layer is one of polypropylene, polyethylene, polyethylene terephthalate, and polyimide.

[0011] Preferably, the material of the suspended plating layer is aluminum, and the material of the drum plating layer is aluminum.

[0012] Preferably, the sheet resistance of the composite conductive film is 32 mΩ-45 mΩ.

[0013] Based on the same inventive principle, in order to achieve the above-mentioned second inventive object, the present invention provides a use of a composite conductive film, and the composite conductive film is applied to a battery current collector.

[0014] Based on the same inventive principle, in order to achieve the third inventive object mentioned above, the present invention provides a composite conductive film preparation process, comprising the following steps:

[0015] A first coating layer is provided on the surface of the thin film carrier layer by a suspension coating machine, wherein the thickness of the first coating layer is 0.01 μm-0.1 μm, and the thickness of the thin film carrier layer is 2 μm-50 μm;

[0016] A second coating layer is disposed on the surface of the first coating layer by a drum coating machine, and the thickness of the second coating layer is 0.7 μm-5 μm.

[0017] Based on the same inventive principle, in order to achieve the third inventive object mentioned above, the present invention also provides a composite conductive film preparation process, comprising the following steps:

[0018] A first coating layer is provided on the surface of the thin film carrier layer by a suspension coating machine, wherein the thickness of the first coating layer is 0.01 μm-0.1 μm, and the thickness of the thin film carrier layer is 4 μm-10 μm;

[0019] A second coating layer is disposed on the surface of the first coating layer by a drum coating machine, and the thickness of the second coating layer is 0.7 μm-2 μm.

[0020] Preferably, the film carrier layer is one of polypropylene, polyethylene, polyethylene terephthalate, and polyimide.

[0021] Preferably, the first coating material is aluminum, and the second coating material is aluminum.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) A suspended plating layer and a drum plating layer are successively arranged on the surface of a thin film carrier layer, wherein the thickness of the suspended plating layer is 0.01 μm-0.1 μm. The suspended plating layer acts as a buffer layer to prevent wrinkles, thereby preventing wrinkles from appearing on the thin film carrier layer when the drum plating layer is arranged, thereby eliminating empty plating lines.

[0024] (2) The suspension coating layer with a thickness of 0.01μm-0.1μm is set by the suspension coating machine. The suspension coating layer is very thin, which can avoid the low efficiency of using only the suspension coating machine. The thickness is further thickened to the set thickness by the drum coating machine on the basis of the suspension coating layer. Under the buffering protection of the suspension coating layer, the film carrier layer does not directly contact the plating roller of the drum coating machine, thereby avoiding wrinkles in the film carrier layer due to excessive heating and cooling, thereby eliminating empty plating lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a cross-sectional view of the conductive composite film of the present invention.

[0026] Figure 2 The figure is a process flow chart of the preparation of the conductive composite film of the present invention.

[0027] Figure 3 The figure is a process flow chart of the preparation of the conductive composite film of the present invention.

[0028] Among them, 1. the first drum-plated layer; 2. the first suspended-plated layer; 3. the thin film carrier layer; 4. the second suspended-plated layer; 5. the second drum-plated layer. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thick", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0031] Embodiment 1

[0032] See also Figure 1 The present embodiment provides a composite conductive film, which includes, from bottom to top, a first drum-plated layer 1, a first suspended-plated layer 2, a thin film carrier layer 3, a second suspended-plated layer 4 and a second drum-plated layer 5, wherein the thin film carrier layer 3 has a thickness of 2 μm-50 μm, the first suspended-plated layer 2 and the second suspended-plated layer 4 have a thickness of 0.01 μm-0.1 μm, and the first drum-plated layer 1 and the second drum-plated layer 5 have a thickness of 0.7 μm-5 μm.

[0033] Suspended plating refers to coating on the surface of the thin film carrier layer 3 by a suspended coating machine. During the coating process, the thin film carrier layer 3 is in a suspended state and is cooled after the coating is completed. There is no defect of empty plating lines. At the same time, the coating heat of the thin film carrier layer 3 cannot be transferred in time, and the deposition efficiency is low. The single coating thickness of the suspended coating machine is about 30nm. To complete a 1μm thick coating, it is necessary to repeat the coating more than 30 times, and it takes about 3 days to complete; drum plating refers to coating on the surface of the thin film carrier layer 3 by a drum coating machine. During the coating process, the back of the thin film carrier layer 3 is tightly attached to a low-temperature large roller for cooling. Drum plating has the defect that the thin film carrier layer 3 is not fully unfolded or not tightly attached before entering the cooling roller, resulting in poor cooling effect of the thin film carrier layer 3 after entering the cooling roller, and wrinkles and abnormal appearance of empty plating lines due to heat during coating.

[0034] In view of the process defects of suspension plating and drum plating, after combining the two processes, a film carrier layer 3 with a thickness of 2μm-50μm is selected, preferably 2μm, 4μm, 8μm, 10μm, 20μm and 40μm, and the film carrier layer 3 is one of polypropylene, polyethylene, polyethylene terephthalate, and polyimide; the first suspension plating layer 2 and the second suspension plating layer 4 are made of aluminum, and the first suspension plating layer 2 and the second suspension plating layer 4 are used as buffer layers; when drum plating is performed on the surfaces of the first suspension plating layer 2 and the second suspension plating layer 4, The thickness of the first drum-plated coating 1 and the second drum-plated coating 5 are both 0.7μm-5μm, preferably 1μm, 2μm, 3μm, and 4μm; the first drum-plated coating 1 and the second drum-plated coating 5 are made of aluminum, and the first drum-plated coating 1 and the second drum-plated coating 5 first contact the first suspended coating 2 and the second suspended coating 4 respectively, and most of the heat is absorbed by the contacted first suspended coating 2 and the second suspended coating 4, and quickly dissipated through the low-temperature large roller, which greatly reduces the influence of heat on the film carrier layer 3, so that the film carrier layer 3 will not wrinkle due to too fast heating, thereby avoiding the empty plating line phenomenon. Therefore, through the integration of the two processes of suspended plating and drum plating, the coating efficiency can be improved, and at the same time, the surface of the conductive composite film can be guaranteed to be smooth and there will be no empty plating lines.

[0035] Embodiment 2

[0036] The difference from the first embodiment is that the film carrier layer used in the second embodiment has a thickness of 4 μm-10 μm, preferably 4 μm or 6 μm, and the thickness of the first drum-plated layer 1 and the second drum-plated layer 5 are 0.7 μm-2 μm, preferably 1 μm and 1.5 μm.

[0037] The composite conductive film disclosed in this embodiment has the same technical solution as that in the first embodiment. Please refer to the first embodiment and no further details will be given here.

[0038] Embodiment 3

[0039] The composite conductive film of Example 1 or Example 2 is applied to a battery current collector, especially as a positive electrode current collector. Compared with the traditional aluminum foil current collector, the composite conductive film of Example 1 or Example 2, when used as a current collector, has a lower density of the thin film carrier layer than that of the aluminum foil, and the total thickness of the composite conductive film can be as small as 6 μm. For example, the thickness of the thin film carrier layer 3 is 5 μm, the thickness of the first drum-plated layer 1 and the second drum-plated layer 5 are both 1 μm, and the thickness of the first suspended-plated layer 2 and the second suspended-plated layer 4 are both 0.03 μm. This can make the current collector thinner or lighter, thereby reducing the weight of the battery and increasing the energy density of the battery.

[0040] Embodiment 4

[0041] See also Figure 2 This embodiment provides a composite conductive film preparation process, comprising the following steps:

[0042] S1: a first coating layer is provided on the surface of the thin film carrier layer by a suspension coating machine, wherein the thickness of the first coating layer is 0.01 μm-0.1 μm, and the thickness of the thin film carrier layer is 2 μm-50 μm; specifically, a thin film carrier layer 3 with a thickness of 2 μm-50 μm is selected, preferably 2 μm, 4 μm, 8 μm, 10 μm, 20 μm and 40 μm, and the thin film carrier layer 3 is one of polypropylene, polyethylene, polyethylene terephthalate, and polyimide; the first coating layer (the first suspension coating layer 2 and the second suspension coating layer 3) is provided on the surface of the thin film carrier layer; The thickness of the floating plating layer 4 is 0.01μm-0.1μm, preferably 0.03μm, 0.05μm, 0.07μm and 0.1μm. The first plating layer (the first suspended plating layer 2 and the second suspended plating layer 4) is made of aluminum, and the first plating layer (the first suspended plating layer 2 and the second suspended plating layer 4) serves as a buffer layer; considering that the single coating thickness of the suspension coating machine is about 30nm, the first coating layer (the first suspended plating layer 2 and the second suspended plating layer 4) requires 1-3 times of suspension plating, and the coating efficiency is greatly improved.

[0043] S2: A second coating is arranged on the surface of the first coating by means of a drum coating machine, and the thickness of the second coating is 0.7μm-5μm; specifically, when the second coating (first drum-plated layer 1 and second drum-plated layer 5) is carried out on the surface of the first coating (first suspended-plated layer 2 and second suspended-plated layer 4), the thickness of the second coating is 0.7μm-5μm, preferably 1μm, 2μm, 3μm, 4μm; the material of the second coating is aluminum.

[0044] After combining the two processes of suspended plating and drum plating, the first plating layer acts as a buffer layer, and the second plating layer first contacts the first plating layer. Most of the heat is absorbed by the first plating layer in contact, and quickly dissipated through the low-temperature large roller, which greatly reduces the impact of heat on the film carrier layer, so that the film carrier layer 3 will not wrinkle due to too rapid heating, thereby avoiding the empty plating line phenomenon. Therefore, through the integration of the two processes of suspended plating and drum plating, the plating efficiency can be improved, and at the same time, it can also ensure that the surface of the conductive composite film is smooth and there are no empty plating lines.

[0045] Embodiment 5

[0046] The difference from the fourth embodiment is that the film carrier layer used in the fifth embodiment has a thickness of 4 μm-10 μm, preferably 4 μm or 6 μm, and the drum plating layer has a thickness of 0.7 μm-2 μm, preferably 1 μm and 1.5 μm.

[0047] The composite conductive film preparation process disclosed in this embodiment has the same technical solution as that in the first embodiment. Please refer to the first embodiment and no further details will be given here.

[0048] To further illustrate the technical effect of the fusion of the two processes of suspension plating and drum plating, the comparative experimental data are shown in Table 1. The conductive composite films of No. 1 to No. 6 in Table 1 adopt a process combining suspension plating and drum plating, and the number of suspension plating is 1 to 3 times, which can not only improve the plating efficiency, but also ensure that the surface of the conductive composite film is flat and there are no empty plating lines. The square resistance range of the conductive composite film is 32mΩ-45mΩ; No. 7 to No. 9 adopt the drum plating process alone, and the final conductive composite film has wrinkles and empty plating line defects and cannot be used normally; No. 10 adopts the suspension plating process alone. In order to achieve a coating thickness of 1μm, it is necessary to repeat the plating for at least 30 times, and the final film formation time consumes 3 days. The efficiency is too low, and in the repeated plating process, perforation is prone to occur, that is, the composite conductive film has several small holes and cannot be used normally. The above comparison of experimental data shows that when the thickness of the suspended plating layer is greatly reduced, the overall film-forming efficiency can be improved. By using the suspended plating layer as a buffer layer, the wrinkles and empty line defects that are prone to occur during drum plating can be effectively avoided. The fusion of the two processes has achieved an unexpected technical effect of leveraging each other's strengths and making up for each other's weaknesses.

[0049] Table 1 Composite conductive film performance parameters

[0050]

Claims

1. A composite conductive film, characterized in that: From bottom to top, it includes a first drum-plated layer, a first suspended-plated layer, a thin film carrier layer, a second suspended-plated layer, and a second drum-plated layer, the thin film carrier layer is 8 μm-50 μm thick, the first suspended-plated layer and the second suspended-plated layer are both 0.07 μm-0.1 μm thick, the first suspended-plated layer and the second suspended-plated layer are suspended 2 or 3 times, and the first drum-plated layer and the second drum-plated layer are both 4 μm-5 μm thick; The square resistance of the conductive composite film ranges from 32mΩ to 45mΩ; The material of the suspended plating layer is aluminum, and the material of the drum plating layer is aluminum.

2. A composite conductive film, characterized in that: From bottom to top, it includes a first drum-plated layer, a first suspended-plated layer, a thin film carrier layer, a second suspended-plated layer, and a second drum-plated layer, the thin film carrier layer is 4 μm thick, the first suspended-plated layer and the second suspended-plated layer are both 0.07 μm-0.1 μm thick, the first suspended-plated layer and the second suspended-plated layer are suspended 2 or 3 times, and the first drum-plated layer and the second drum-plated layer are both 0.7 μm or 1.5 μm thick; The square resistance of the conductive composite film ranges from 32mΩ to 45mΩ; The material of the suspended plating layer is aluminum, and the material of the drum plating layer is aluminum.

3. The composite conductive film according to claim 1 or 2, characterized in that: The film carrier layer is one of polypropylene, polyethylene, polyethylene terephthalate and polyimide.

4. The composite conductive film according to any one of claims 1 to 3 is used as a battery current collector.

5. A composite conductive film preparation process, characterized in that: The following steps are involved: A first coating layer is provided on the surface of the thin film carrier layer by a suspension coating machine, wherein the thickness of the first coating layer is 0.07 μm-0.1 μm, the thickness of the thin film carrier layer is 8 μm-50 μm, and the number of suspension coatings of the first coating layer is 2 or 3 times; Arranging a second coating layer on the surface of the first coating layer by a drum coating machine, wherein the thickness of the second coating layer is 4 μm-5 μm; The square resistance of the conductive composite film ranges from 32mΩ to 45mΩ; The material of the suspended plating layer is aluminum, and the material of the drum plating layer is aluminum.

6. A composite conductive film preparation process, characterized in that: The following steps are involved: A first coating layer is provided on the surface of the thin film carrier layer by a suspension coating machine, wherein the thickness of the first coating layer is 0.07 μm-0.1 μm, the thickness of the thin film carrier layer is 4 μm, and the number of suspension coatings of the first coating layer is 2 or 3 times; Arranging a second coating layer on the surface of the first coating layer by a drum coating machine, wherein the thickness of the second coating layer is 0.7 μm or 1.5 μm; The square resistance of the conductive composite film ranges from 32mΩ to 45mΩ; The material of the suspended plating layer is aluminum, and the material of the drum plating layer is aluminum.

7. The process for preparing a composite conductive film according to claim 5 or 6, characterized in that: The film carrier layer is one of polypropylene, polyethylene, polyethylene terephthalate and polyimide.

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