A method for preparing ultra-thin electrolytic copper foil with high oxidation resistance

Abstract

The present invention discloses a method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance. The method comprises using a copper sulfate + sulfuric acid solution as an electrolyte, adding 10 to 100 mg / L of a metallic aluminum inorganic salt and 5 to 20 mL / L of hydrofluoric acid to the electrolyte, and performing direct current electrolysis to obtain an electrolytic copper foil. The electrolytic copper foil is then peeled off to obtain an ultra-thin electrolytic copper foil. In the present invention, by adding an appropriate amount of metallic aluminum inorganic salt and hydrofluoric acid to the electrolyte, the hydrofluoric acid can preferentially orient the (220) crystal plane of the copper foil, and aluminum and copper ions form a copper-aluminum microalloy through co-deposition. Therefore, the prepared ultra-thin electrolytic copper foil has good oxidation resistance and basically does not change color when stored in a conventional environment for one month.

Description

Technical Field

[0001] The present invention relates to the technical field of copper foil production, and in particular to a method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance. Background Art

[0002] Ultra-thin electrolytic copper foil is an important base material for lithium-ion power batteries. However, it is easily oxidized and corroded during production and application, increasing the battery's internal resistance, reducing its capacity, and affecting its performance and stability. Traditionally, the surface passivation process for ultra-thin electrolytic copper foil involves treating it with chromic anhydride to form a dense antioxidant layer on the foil surface, thereby improving its antioxidant properties. However, the introduction of chromium makes it difficult to meet the product's chromium-free and environmental requirements. Currently, researchers are exploring methods such as coating the copper foil surface with organic matter or electroplating an alloy layer on the copper foil surface to replace the traditional chromic anhydride anti-oxidation process. Summary of the Invention

[0003] The purpose of this project is to provide a method for preparing ultra-thin electrolytic copper foil with high oxidation resistance. By adding appropriate amounts of aluminum nitrate and hydrofluoric acid to the electrolyte, the ultra-thin electrolytic copper foil prepared has good oxidation resistance and basically does not change color when stored for one month under normal environmental conditions.

[0004] To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: a method for preparing ultra-thin electrolytic copper foil with high oxidation resistance, wherein copper sulfate + sulfuric acid solution is used as an electrolyte, 10-100 mg / L of metallic aluminum inorganic salt and 5-20 mL / L of hydrofluoric acid are added to the electrolyte for direct current electrolysis to obtain electrolytic copper foil, and the electrolytic copper foil is peeled off to obtain ultra-thin electrolytic copper foil.

[0005] Preferably, the metallic aluminum inorganic salt is aluminum sulfate or aluminum nitrate, or a mixture of the two.

[0006] Preferably, the electrolyte temperature is 55°C.

[0007] Preferably, the current density of direct current electrolysis is 1000A / m 2 , the electrolysis time is 4 minutes.

[0008] Preferably, a titanium sheet plated with ruthenium and iridium is used as the anode, and a titanium sheet is used as the cathode.

[0009] Preferably, in the electrolyte, the concentration of copper sulfate is 80 g / L, and the concentration of sulfuric acid is 0.2 mol / L.

[0010] The beneficial effects of the present invention are as follows:

[0011] Metal aluminum inorganic salt and hydrofluoric acid are added to the electrolyte. Hydrofluoric acid can make the copper foil (220) crystal plane preferentially oriented, and aluminum and copper ions form copper-aluminum microalloy through co-deposition. Therefore, the prepared ultra-thin electrolytic copper foil has good antioxidant properties and basically does not change color when stored in a normal environment for 1 month. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Actual photos of the ultra-thin electrolytic copper foil prepared by adding metallic aluminum inorganic salt and hydrofluoric acid and the ultra-thin electrolytic copper foil samples of Comparative Example 1 after being stored under normal conditions for one month.

[0013] Figure 2 XRD patterns of the ultra-thin electrolytic copper foil prepared by adding metallic aluminum inorganic salt and hydrofluoric acid and the ultra-thin electrolytic copper foil sample of Comparative Example 1. DETAILED DESCRIPTION

[0014] The following is a further detailed description of the implementation of this solution. Obviously, the described embodiments are only a part of the embodiments of this solution, rather than an exhaustive list of all the embodiments.

[0015] A method for preparing ultra-thin electrolytic copper foil with high oxidation resistance comprises the following steps:

[0016] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, a certain amount of metallic aluminum inorganic salt and hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55 ℃, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with high oxidation resistance of 6 μm was obtained by peeling.

[0017] In one embodiment, the amount of aluminum sulfate used is 10 mg / L, and the amount of hydrofluoric acid used is 5 mL / L.

[0018] In one embodiment, the amount of aluminum sulfate used is 10 mg / L, and the amount of hydrofluoric acid used is 20 mL / L.

[0019] In one embodiment, the amount of aluminum sulfate used is 100 mg / L, and the amount of hydrofluoric acid used is 5 mL / L.

[0020] In one embodiment, the amount of aluminum sulfate used is 100 mg / L, and the amount of hydrofluoric acid used is 20 mL / L.

[0021] In one embodiment, the amount of aluminum nitrate used is 50 mg / L, and the amount of hydrofluoric acid used is 10 mL / L.

[0022] In one embodiment, the amount of aluminum sulfate used is 20 mg / L, the amount of aluminum nitrate used is 30 mg / L, and the amount of hydrofluoric acid used is 15 mL / L.

[0023] The present application is further explained below through specific examples. Example 1

[0024] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 10 mg / L of aluminum sulfate and 5 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55°C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month. Example 2

[0025] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 10 mg / L of aluminum sulfate and 20 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55 °C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month. Example 3

[0026] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 100 mg / L of aluminum sulfate and 5 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55 °C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month. Example 4

[0027] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 100 mg / L of aluminum sulfate and 20 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55 ° C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time is 4 minutes. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm is obtained by peeling and stored in a normal environment for 1 month. Example 5

[0028] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 50 mg / L of aluminum nitrate and 10 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55 °C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month. Example 6

[0029] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, 20 mg / L of aluminum sulfate, 30 mg / L of aluminum nitrate and 15 mL / L of hydrofluoric acid were added to the electrolyte, the electrolyte temperature was 55°C, and direct current electrolysis was performed to obtain electrolytic copper foil at a current density of 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month.

[0030] Comparative Example 1

[0031] A titanium sheet plated with ruthenium and iridium was used as the anode, a titanium sheet was used as the cathode, a copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate was 80 g / L, the concentration of sulfuric acid was 0.2 mol / L, the electrolyte temperature was 55 °C, and a direct current electrolysis was performed to obtain electrolytic copper foil. The current density was 1000 A / m 2 The electrolysis time was 4 min. After washing with deionized water and drying with cold air, the ultra-thin electrolytic copper foil with a thickness of 6 μm was obtained by peeling and stored in a conventional environment for 1 month.

[0032] from Figure 1It can be clearly seen that the surface of the unadded ultra-thin electrolytic copper foil changed significantly after being stored in a conventional environment for one month, indicating that the ultra-thin electrolytic copper foil is easily oxidized. However, the ultra-thin electrolytic copper foil prepared by adding metallic aluminum inorganic salt and hydrofluoric acid basically did not change color after being stored in a conventional environment for one month (the changes of the ultra-thin electrolytic copper foil obtained in each embodiment are basically the same, so only one picture is provided. Since color pictures cannot be submitted, Figure 1 The grayscale image shows that the color difference between the comparative example and the example is obvious when observed in real life), indicating that it has good antioxidant properties. The addition of hydrofluoric acid and metallic aluminum inorganic salt can promote the preferred orientation of the copper (220) crystal plane (the XRD patterns of the examples are similar, so only the XRD patterns are provided here). Figure 2 ,from Figure 2 It can be clearly seen that after the addition of inorganic aluminum metal salts, the relative strength of the (220) crystal plane of the copper foil is significantly enhanced). The preferential orientation of the (220) crystal plane of the copper material is conducive to improving its oxidation resistance (Nature, 2020, 586:390-394). At the same time, aluminum ions and copper ions can form copper-aluminum microalloys through co-deposition. The existence of the copper-aluminum microalloy structure can improve the performance of the copper foil. Therefore, the ultra-thin electrolytic copper foil prepared by adding metal aluminum inorganic salts and hydrofluoric acid has good oxidation resistance.

[0033] The specific embodiments described above further illustrate the objectives, technical solutions, and technical effects of the present invention in detail. It should be understood that the above description is merely a specific embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the spirit and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing ultra-thin electrolytic copper foil with high oxidation resistance, characterized in that: Using copper sulfate + sulfuric acid solution as the electrolyte, with the concentration of copper sulfate being 80 g / L and the concentration of sulfuric acid being 0.2 mol / L, 10-100 mg / L of metallic aluminum inorganic salt and 5-20 mL / L of hydrofluoric acid were added to the electrolyte for direct current electrolysis to obtain electrolytic copper foil. During the electrolysis process, hydrofluoric acid preferentially oriented the 220 crystal plane of the copper foil, and aluminum and copper ions formed a copper-aluminum microalloy through co-deposition. The electrolytic copper foil was then peeled off to obtain an ultra-thin electrolytic copper foil.

2. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, wherein: The metallic aluminum inorganic salt is aluminum sulfate or aluminum nitrate or a mixture of the two.

3. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, wherein: The electrolyte temperature is 55°C.

4. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, wherein: The current density of DC electrolysis is 1000A / m 2 , the electrolysis time is 4 minutes.

5. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, wherein: The electrolytic copper foil is washed with deionized water, dried with cold air, and then peeled off.

6. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, wherein: The titanium sheet coated with precious metal is used as the anode and the titanium sheet is used as the cathode.

7. The method for preparing an ultra-thin electrolytic copper foil with high oxidation resistance according to claim 1, characterized in that: A titanium sheet plated with ruthenium and iridium is used as the anode, and a titanium sheet is used as the cathode.

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