Resin-graphite emulsion composite copper foil, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a resin-graphite emulsion composite copper foil, and a preparation method therefor and the use thereof. The preparation method comprises the following steps: S1, subjecting a resin film to oil removal and roughening treatments, then coating the surface of the resin film with a graphite conducting layer by using a graphite emulsion suspension, and drying same to obtain a graphite-resin-graphite structural body; S2, depositing a copper foil on the graphite layer of the graphite-resin-graphite structural body, so as to form a copper-graphite-resin-graphite-copper structural body; and S3, subjecting the copper-graphite-resin-graphite-copper structural body to an anti-oxidation treatment, so as to obtain a resin-graphite emulsion composite copper foil. The resin-graphite emulsion composite copper foil provided in the present invention does not need to be subjected to expensive treatments such as evaporation and sputtering, and has the advantages of a low cost, a simple process and a good conductivity. The resin is subjected to a conducting treatment by means of impregnation with the graphite emulsion, and the binding force of the copper foil electrodeposited on the surface of the graphite layer is increased by means of the pinning effect of graphite and copper particles.

Description

Resin-graphite emulsion composite copper foil and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of composite copper foil, and in particular to a resin-graphite emulsion composite copper foil and a preparation method and application thereof. Background Art

[0002] Composite copper foil is a thin film material with a polymer base film as the middle layer and copper as the coating layer. The middle layer is generally PET / PP / PI. The metal material is applied to the substrate surface using evaporation / magnetron sputtering or water electroplating technology. Other functional metals are used as the coating layer on each side to form a sandwich conductive film material.

[0003] Composite copper foil is soft, ductile, and compressive. Its use as a negative electrode in lithium batteries effectively inhibits the formation of lithium dendrites, reduces the risk of internal short circuits, reduces battery weight, and improves battery energy density and safety. However, the thin PET film rolls used for composite copper foil require sophisticated magnetron sputtering equipment, which carries high investment and depreciation costs. The sputtered seed copper is thin and has high resistivity, leading to large variations in the thickness of the electroplated copper foil layer. The thin PET film is prone to deformation during the fabrication process. PET / PP composite copper foil has poor conductivity in the middle layer, while PI offers good performance but is expensive. Depositing copper on polymers, whether by sputtering or vapor deposition, is difficult.

[0004] Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a resin-graphite emulsion composite copper foil and its preparation method and application. The present invention does not require expensive treatments such as evaporation and sputtering, and has the advantages of low cost and simple process.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of the present invention is to provide a method for preparing a resin-graphite emulsion composite copper foil, comprising the following steps:

[0008] S1, after the resin is degreased and roughened, it is subjected to a conductive treatment, that is, the resin film is passed through a graphite emulsion suspension to coat the surface of the resin film with a graphite conductive layer, and then dried and solidified to obtain a graphite-resin-graphite structure;

[0009] S2. depositing copper foil on the graphite conductive layer of the graphite-resin-graphite structure to form a copper-graphite-resin-graphite-copper structure;

[0010] S3. Performing an anti-oxidation treatment on the copper-graphite-resin-graphite-copper structure to obtain a resin-graphite emulsion composite copper foil.

[0011] In some embodiments, the resin film degreasing and roughening treatment comprises: alkali washing the resin film in a sodium hydroxide solution with a concentration of 5-10% and a temperature of 40-65° C. for 5-30 minutes, and after washing, roughening the resin film with a roughening solution at a temperature of 50-60° C. for 5-10 minutes, wherein the roughening solution comprises sulfuric acid and an oxidant, and the oxidant is selected from at least one of chromic acid, chromic anhydride, and potassium permanganate;

[0012] In some specific embodiments of the present invention, the roughening solution preferably contains 80-90% pure sulfuric acid, 4-6% pure chromic acid, and the balance water; the roughening solution preferably contains 20-60% pure sulfuric acid, 5-10% pure potassium permanganate, and the balance water.

[0013] In some embodiments, in step S1 , the resin film has a thickness of 1.0-5.0 μm, and the resin film is selected from at least one of ABS resin, polypropylene resin, PET resin, polyurethane, polytetrafluoroethylene resin, phenolic resin, and epoxy resin.

[0014] In some embodiments, in step S1, the graphite emulsion suspension contains low-resistance conductive graphite emulsion or a graphite emulsion mixture; the graphite emulsion mixture includes graphite emulsion and acrylic resin, the mass ratio of graphite emulsion to acrylic resin is 85-95:5-15, the graphite particle size D50 is 2-200 nm, and the graphite emulsion density is 1.9-2.3 g / cm 3 The speed at which the resin film passes through the graphite emulsion suspension is 0.1-2.5 cm / s, and the thickness of the graphite-resin-graphite structure is 1.0-6.0 μm.

[0015] In some embodiments, the graphite suspension further contains copper powder, the mass ratio of graphite to copper powder is 20-250:1, and the particle size of the copper powder is 15-500 nm.

[0016] The present invention uses a suspension in which graphite is evenly dispersed, and adds nano copper powder to the graphite emulsion solution, so that a resin film is evenly covered with a graphite / copper composite layer, resulting in the graphite layer of the graphite-resin-graphite structure being provided with nano copper particles. The nano copper particles can become the subsequent preferential deposition sites, and the binding force between the graphite and the copper deposition layer is enhanced through the pinning effect.

[0017] In some embodiments, in step S2, the copper foil layer has a thickness of 0.5-5 μm.

[0018] In some embodiments, in step S2, the deposition parameters include: a current density of 0.1-10 A / dm 2 , the deposition liquid is selected from at least one of copper pyrophosphate and copper sulfate system copper plating solutions; wherein the copper ion concentration in the copper sulfate system copper plating solution is 60-120 g / L, and the sulfuric acid concentration is 100-150 g / L.

[0019] In some embodiments, the anti-oxidation treatment is an electrodeposition or immersion treatment.

[0020] It should be noted that the antioxidant agent used in the electrodeposition or immersion treatment is selected from at least one of chromium trioxide, glucose, BTA, EDTA, triethanolamine, and deionized water.

[0021] In some specific embodiments, the anti-oxidation treatment is electroplating chromium, and the electroplating step includes: placing the copper-graphite-resin-graphite-copper structure obtained in step S2 into an antioxidant reagent for electroplating; wherein the current density is 1-6A / dm 2 , the temperature of the antioxidant agent is 25-35°C, the concentration of the antioxidant agent is 0.4-10g / L, and the electrodeposition time is 3-10s.

[0022] In some other specific embodiments, the antioxidant treatment is an immersion treatment, and the immersion treatment step includes: immersing the copper-graphite-resin-graphite-copper structure obtained in step S2 flatly in an antioxidant agent without washing and drying; wherein the immersion time is 3-15s, the antioxidant agent temperature is 20-40°C, the drying temperature is 50-110°C, and hot air drying is used.

[0023] A second aspect of the present invention is to provide a resin-graphite emulsion composite copper foil.

[0024] The third aspect of the present invention is to provide the use of resin-graphite emulsion composite copper foil in the preparation of negative electrode current collectors for lithium batteries, sodium batteries, potassium batteries, magnesium batteries, calcium batteries, and aluminum batteries.

[0025] The present invention includes the following beneficial effects:

[0026] (1) The composite copper foil provided by the present invention has the advantages of good conductivity, easy preparation of the intermediate layer, low cost, and a wide range of adjustable thickness. The thickness of the composite copper foil can be further reduced, the process is simple, and no expensive processing methods such as evaporation and sputtering are required.

[0027] (2) The preparation method provided by the present invention treats the resin for conductive treatment by impregnation with graphite emulsion, and increases the bonding strength of the electrodeposited copper foil on the surface of the graphite layer through the pinning effect of graphite and copper particles. When copper is directly plated on graphite, the bonding strength between graphite and copper is weak, resulting in low peeling strength between layers of the composite copper foil during use and easy formation of cracks. Chemical copper plating and electroplating copper thickening methods easily lead to low copper plating efficiency and unstable plating solution. The present invention utilizes the pinning effect of graphite and copper particles to increase the bonding strength of the electrodeposited copper foil on the surface of the graphite layer, eliminating the need for chemical copper plating. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic structural diagram of the resin-graphite emulsion composite copper foil provided by the present invention, in which 1 is the copper foil and 2 is the graphite-resin-graphite structure. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be understood as limiting the present invention.

[0030] Example 1

[0031] A method for preparing a resin-graphite emulsion composite copper foil comprises the following steps:

[0032] S1: Conductive treatment of resin film

[0033] An ABS film with a thickness of 2.0 μm was selected. The resin film was alkaline washed in a sodium hydroxide solution with a concentration of 5% and a temperature of 60°C for 15 minutes. After washing, the film was roughened with a roughening solution at a temperature of 50°C for 5 minutes. The roughening solution contained 80% pure sulfuric acid, 4% pure chromic acid, and the remainder water. After degreasing and roughening, a conductive treatment was performed. The treated resin film was passed through a graphite emulsion suspension at a speed of 0.2 cm / s. The graphite emulsion suspension consisted of electric graphite emulsion, acrylic resin, and copper powder. In the graphite emulsion suspension, the mass ratio of graphite emulsion to acrylic resin was 95:5, the mass ratio of graphite to copper powder was 22:1, and the density of the graphite emulsion was 2.2 g / cm 3 The particle size of the copper powder is 200 nm, the graphite particle size D50 is 180 nm, and the resin film is covered with a graphite conductive layer on both sides. After drying, a graphite-resin-graphite structure is obtained, and the thickness of the graphite-resin-graphite structure is 2.5 μm.

[0034] S2: Electroplated copper

[0035] Copper foil is deposited on both sides of the graphite layer of the graphite-resin-graphite structure to form a copper-graphite-resin-graphite-copper structure. The deposition current density is 1.0 A / dm, and 1.0 μm is deposited on each side. The deposition liquid is a copper sulfate and sulfuric acid system plating solution with a copper ion concentration of 90 g / L and a sulfuric acid concentration of 120 g / L.

[0036] S3: Electroplating Anti-Oxidation

[0037] The copper-graphite-resin-graphite-copper structure is subjected to an anti-oxidation treatment to obtain a resin-graphite emulsion composite copper foil. The anti-oxidation treatment is performed by electrodeposition of chromate, wherein the current density of the electrodeposition of chromium is 2A / dm 2 The plating solution is a mixed solution of 0.2g / L chromium trioxide and 4g / L glucose, the plating temperature is 30℃, the plating concentration is 5g / L, and the electrodeposition time is 3s.

[0038] Example 2

[0039] The preparation steps are the same as those in Example 1, except that the ABS resin is replaced by polypropylene resin (PP).

[0040] Comparative Example 1

[0041] The preparation steps are the same as those in Example 1, except that the graphite emulsion does not contain nano-scale conductive copper powder.

[0042] Test example: tensile properties test

[0043] The 4.5 μm copper foil obtained above was tested for adhesion between the coating and the substrate according to ASTM E345-16, Standard Test Method for Tensile Testing of Metal Foil. The copper foil was cut into 0.5-inch widths using a double-edged cutter (JDC, THWING-ALBERT). The tensile properties of the copper foil were then tested using a single tensile testing machine (Dynamics, LD22.502). The test results are shown in Table 1. The results show that the adhesion and tensile strength of the composite copper foils provided in Examples 1 and 2 of this application were superior to those of Comparative Example 1.

[0044] Table 1

[0045] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A preparation method of a resin-graphite milk composite copper foil, characterized in that, it comprises the following steps: S1. After the resin film is degreased and roughened, it passes through a graphite milk suspension to coat the surface of the resin film with a graphite conductive layer, and after drying, a graphite-resin-graphite structure is obtained; S2. Deposit a copper foil on the graphite conductive layer of the graphite-resin-graphite structure to form a copper-graphite-resin-graphite-copper structure; S3. Perform an antioxidant treatment on the copper-graphite-resin-graphite-copper structure to obtain a resin-graphite milk composite copper foil.

2. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, in the step S1, the degreasing and roughening treatment of the resin film is: the resin film is alkali-washed in a sodium hydroxide solution with a concentration of 5-10% and a temperature of 40-65°C for 5-30 minutes, and after washing, it is roughened with a roughening solution at a temperature of 50-60°C for 5-10 minutes; the roughening solution includes pure sulfuric acid and an oxidant, and the oxidant is selected from at least one of chromic acid, chromium anhydride, and potassium permanganate.

3. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, in the step S1, the thickness of the resin film is 1.0-5.0 μm, and the resin film is selected from at least one of ABS resin, polypropylene resin, PET resin, polyurethane, polytetrafluoroethylene resin, phenolic resin, and epoxy resin.

4. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, In the step S1, the graphite milk suspension contains graphite milk and acrylic resin, and the mass ratio of the graphite milk to the acrylic resin is 85-95:5-15. The graphite particle size D50 is 2-200 nm, and the density of the graphite milk is 1.9-2.3 g / cm 3 , the speed of the resin film passing through the graphite milk suspension is 0.1-2.5 cm / s, and the thickness of the graphite-resin-graphite structure is 1.0-6.0 μm.

5. The preparation method of the resin-graphite milk composite copper foil according to claim 4, characterized in that, the graphite milk suspension further contains copper powder, and the mass ratio of graphite to copper powder is 20-250:1, and the particle size of the copper powder is 15-500 nm.

6. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, in the step S2, the thickness of the copper foil layer is 0.5-5 μm.

7. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, In the step S2, the deposition parameters include: the current density is 0.1-10 A / dm 2 , and the deposition solution is selected from at least one of copper pyrophosphate and copper sulfate system copper plating solutions; in the copper sulfate system copper plating solution, the copper ion concentration is 60-120 g / L, and the sulfuric acid concentration is 100-150 g / L.

8. The preparation method of the resin-graphite milk composite copper foil according to claim 1, characterized in that, in the step S3, the antioxidant treatment is electroplating or immersion treatment.

9. A resin-graphite milk composite copper foil prepared by the preparation method according to any one of claims 1-8.

10. Application of the resin-graphite milk composite copper foil according to claim 9 in preparing a negative current collector of a lithium-ion battery, a sodium battery, a potassium battery, a magnesium battery, a calcium battery, or an aluminum battery.

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