An additive and method for preparing high-tensile-strength and high-elongation ultra-thin electrolytic copper foil

Abstract

This proposal discloses an additive and method for producing ultra-thin electrolytic copper foil with high tensile strength and high elongation. The additive comprises an inorganic nitrate and an organic compound; the inorganic nitrate is one or a combination of ammonium nitrate, copper nitrate, and bismuth nitrate; and the organic compound is a crown ether, a cyclic alcohol, and glycolic acid. By adding the inorganic nitrate / organic compound additive, the present invention produces ultra-thin electrolytic copper foil with a thickness of 6 μm or less, achieving a tensile strength exceeding 500 MPa and an elongation exceeding 5%.

Description

Technical Field

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

[0002] The mechanical properties of ultra-thin electrolytic copper foil, such as tensile strength and elongation, are closely related to the copper foil electrodeposition process and microstructure. Excluding the influence of the electrolysis process, additives are usually used to regulate the ultra-thin copper foil electrodeposition process and microstructure, thereby obtaining ultra-thin electrolytic copper foil with excellent tensile strength and elongation properties. Currently, the additives developed and used are mainly organic additives. In the performance regulation of ultra-thin electrolytic copper foil, there is generally a mutual constraint between the tensile strength and elongation properties of the copper foil, making it difficult to meet the high tensile strength and high elongation mechanical properties requirements of high-performance lithium-ion batteries for ultra-thin electrolytic copper foil. Therefore, there is an urgent need to develop new and efficient additives to regulate the preparation of ultra-thin electrolytic copper foil with high tensile strength and high elongation. Summary of the Invention

[0003] The purpose of this scheme is to provide an additive and method for preparing ultra-thin electrolytic copper foil with high tensile strength and high elongation. The additive is composed of inorganic nitrate and organic matter. The ultra-thin electrolytic copper foil prepared by this additive has a tensile strength of more than 500MPa and an elongation of more than 5%.

[0004] Another object of this solution is to provide a method for preparing ultra-thin electrolytic copper foil with high tensile strength and high elongation.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] An additive for preparing high-tensile strength and high-elongation ultra-thin electrolytic copper foil, the additive consisting of an inorganic nitrate and an organic matter; the inorganic nitrate is one or a composite of ammonium nitrate, copper nitrate, and bismuth nitrate; the organic matter is a crown ether, a cyclic alcohol, and glycolic acid; the dosage of the inorganic nitrate is 5-50 mg / L; the dosage of the crown ether is 1-5 mg / L; the dosage of the cyclic alcohol is 1-10 mL / L; and the dosage of the glycolic acid is 5-20 mL / L.

[0007] Specifically, the crown ether is diaza-18-crown-6 or 18-crown-6.

[0008] Specifically, the cyclic alcohol is cyclopropanol or cyclohexanol.

[0009] On the other hand, a method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation is provided. The method uses copper sulfate + sulfuric acid solution as an electrolyte, and inorganic nitrate and organic matter as additives to perform direct current electrolysis to obtain the electrolytic copper foil; the inorganic nitrate is one or a combination of ammonium nitrate, copper nitrate, and bismuth nitrate; the organic matter is crown ether, cyclic alcohol, and glycolic acid; the amount of inorganic nitrate is 5-50 mg / L; the amount of crown ether is 1-5 mg / L; the amount of cyclic alcohol is 1-10 mL / L; and the amount of glycolic acid is 5-20 mL / L.

[0010] Preferably, the concentration of copper sulfate in the copper sulfate + sulfuric acid solution is 80-120 g / L, and the concentration of sulfuric acid is 0.3-3 mol / L.

[0011] Preferably, the current density during electrolysis is 2000-6000 A / m 2 .

[0012] Preferably, the electrolyte temperature during electrolysis is 50-60°C.

[0013] Preferably, the electrolysis duration is 1 to 3 minutes.

[0014] Preferably, a titanium sheet plated with ruthenium and iridium is used as the anode, and a titanium sheet is used as the cathode.

[0015] The beneficial effects of the present invention are as follows: through the inorganic nitrate and organic composite additive of the present invention, the electrodeposition process and microstructure of ultra-thin copper foil can be regulated to obtain copper foil with small grains and dense structure. Therefore, the prepared ultra-thin electrolytic copper foil with a thickness of 6 μm or less exhibits mechanical properties such as high tensile strength and high elongation, with a tensile strength of more than 500 MPa and an elongation of more than 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Scanning electron microscope images of copper foil, where (a) contains composite additives and (b) does not contain additives. DETAILED DESCRIPTION

[0017] 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, and are not an exhaustive list of all embodiments. It should be noted that the embodiments and features in the embodiments of this solution can be combined with each other unless they conflict.

[0018] Ultra-thin electrolytic copper foil with high tensile strength and high elongation is a trend in the development of lithium battery copper foil. The inventors of this application have achieved ultra-thin electrolytic copper foil with high tensile strength and high elongation by adding a composite additive composed of an inorganic nitrate and an organic compound to the electrolyte. The additive consists of an inorganic nitrate, a crown ether, a cyclic alcohol, and glycolic acid. The nitrate is used in an amount of 5-50 mg / L, the crown ether in an amount of 1-5 mg / L, the cyclic alcohol in an amount of 1-10 mL / L, and the glycolic acid in an amount of 5-20 mL / L.

[0019] In one embodiment, the inorganic nitrate is one or a combination of ammonium nitrate, copper nitrate, and bismuth nitrate; the crown ether is diaza 18-crown-6 or 18-crown-6; and the cycloalcohol is cyclopropanol or cyclohexanol.

[0020] The method for preparing copper foil by electrolyzing a copper sulfate + sulfuric acid solution using the above additives comprises the following steps:

[0021] A titanium sheet plated with ruthenium and iridium is used as the anode and a pure titanium sheet is used as the cathode. Under the action of a DC power supply, a certain current density is controlled, inorganic nitrates and organic composite additives are added, and the copper sulfate + sulfuric acid solution is electrolyzed at a constant temperature. By controlling the electrolysis time, a high-tensile and high-elongation ultra-thin electrolytic copper foil with a thickness of 6μm or less is prepared.

[0022] In one embodiment, the concentration of copper sulfate in the copper sulfate+sulfuric acid solution is 80-128 g / L, and the concentration of sulfuric acid is 0.3-3 mol / L.

[0023] In one embodiment, the current density during electrolysis is 2000-6000 A / m 2 .

[0024] In one embodiment, the temperature of the copper sulfate solution is kept constant at 50-60° C. during electrolysis.

[0025] In one embodiment, the electrolysis duration is 1 to 3 minutes.

[0026] In one embodiment, the amount of inorganic nitrate in the electrolyte is 5-50 mg / L, the amount of crown ether is 1-5 mg / L, the amount of cyclic alcohol is 1-10 mL / L, and the amount of glycolic acid is 5-20 mL / L.

[0027] In Comparative Example 1, the composite additives were free of cyclic alcohol and glycolic acid, and an electrolytic copper foil with a thickness of 6 μm was prepared.

[0028] In Comparative Example 2, an electrolytic copper foil with a thickness of 6 μm was prepared by using the present invention without any additives.

[0029] The present application is further explained below through specific examples.

[0030] Example 1

[0031] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 A composite additive was added to the electrolyte, containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, 3 mL / L diaza-18-crown ether-6, 4 mL / L cyclohexanol, and 10 mL / of glycolic acid. Copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 50°C, and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 6 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 635 MPa and the elongation was 6.5%.

[0032] Example 2

[0033] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 A composite additive was added to the electrolyte, containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, 3 mL / L diaza-18-crown ether-6, 4 mL / L cyclohexanol, and 10 mL / of glycolic acid. Copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 100 g / L, and the concentration of sulfuric acid was 1.0 mol / L. The temperature of the electrolyte was maintained at 50°C, and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 6 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 668 MPa and the elongation was 6.2%.

[0034] Example 3

[0035] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 3000A / m 2 A composite additive was added to the electrolyte, containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, 3 mL / L diaza-18-crown ether-6, 4 mL / L cyclohexanol, and 10 mL / of glycolic acid. Copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 50°C, and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 5 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 535 MPa and the elongation was 5.8%.

[0036] Example 4

[0037] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 A composite additive was added to the electrolyte, containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, 3 mL / L diaza-18-crown ether-6, 4 mL / L cyclohexanol, and 10 mL / of glycolic acid. Copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 60°C, and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 6 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 518 MPa and the elongation was 5.3%.

[0038] Example 5

[0039] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 A composite additive was added to the electrolyte, containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, 3 mL / L diaza-18-crown ether-6, 4 mL / L cyclohexanol, and 10 mL / of glycolic acid. Copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 50°C, and the power was applied for 2 minutes to prepare an electrolytic copper foil with a thickness of 4 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 568 MPa and the elongation was 5.6%.

[0040] Example 6

[0041] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 , a composite additive was added to the electrolyte, the additive containing 10 mg / L ammonium nitrate, 20 mg / L copper nitrate, 5 mg / L bismuth nitrate, 5 mL / L 18 crown 6, 8 mL / L cyclopropanol, and 5 mL / glycolic acid. The concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 50°C and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 6 μm. After testing, the tensile strength of the prepared electrolytic copper foil was 508 MPa and the elongation was 5.1%.

[0042] Comparative Example 1

[0043] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2A composite additive was added to the electrolyte, the composite additive containing 5 mg / L ammonium nitrate, 20 mg / L copper nitrate, 10 mg / L bismuth nitrate, and 3 mL / L diaza-18-crown ether-6. A copper sulfate + sulfuric acid solution was used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution was 128 g / L, and the concentration of sulfuric acid was 0.5 mol / L. The temperature of the electrolyte was maintained at 50°C and the power was applied for 3 minutes to prepare an electrolytic copper foil with a thickness of 6 μm. After testing, the prepared electrolytic copper foil had a tensile strength of 432 MPa and an elongation of 3.5%.

[0044] Comparative Example 2

[0045] The titanium sheet plated with ruthenium and iridium is used as the anode and the titanium sheet is used as the cathode. Under the action of DC power supply, the current density is controlled to be 4000A / m 2 Copper sulfate + sulfuric acid solution is used as the electrolyte, the concentration of copper sulfate in the copper sulfate solution is 128g / L, and the concentration of sulfuric acid is 0.5mol / L. The temperature of the electrolyte is maintained at 50°C, and the power is applied for 3 minutes. The prepared electrolytic copper foil has a thickness of 6μm. After testing, the tensile strength of the prepared electrolytic copper foil is 318MPa and the elongation is 2.8%.

[0046] Table 1 lists the thickness and tensile strength of the electrolytic copper foil prepared in each example. The copper foil thickness was measured directly using a Mitutoyo digital outside micrometer. The tensile strength and elongation were tested using a CMT-6103 universal testing machine in accordance with GB / T 228.1-2010. Samples were 15 x 150 mm rectangular strips, with a gauge length of 50 mm and a chuck speed of 10 mm / min. Three strips were taken from each sample, for a total of three samples. The strip that broke in the middle was used as the valid data. Electron backscatter diffraction (EBSD) was used to determine the grain size of the copper foil.

[0047] Table 1

[0048]

[0049] From Table 1 and Figure 1 It can be seen that compared with the ultra-thin electrolytic copper foil prepared without any additives, the ultra-thin electrolytic copper foil prepared by adding composite additives has smaller grain size and smaller and more compact microstructure particles, so it has higher tensile strength and greater elongation. By adding an appropriate amount of inorganic nitrate, nitrate is reduced to NH 4+ , NH 4+ Can be used with Cu 2+ Complexation changes the copper electrodeposition process and refines the grains. Yttrium can enter the interior of the copper foil through co-deposition, forming more dislocations or substructures. Therefore, the tensile strength and elongation of the ultra-thin electrolytic copper foil can be significantly improved at the same time.

[0050] 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. An additive for preparing ultra-thin electrolytic copper foil with high tensile strength and high elongation, characterized in that: The additive consists of an inorganic nitrate and an organic matter; the inorganic nitrate is one or a combination of ammonium nitrate, copper nitrate, and bismuth nitrate; the organic matter is a crown ether, a cyclic alcohol, and glycolic acid; the crown ether is diaza-18-crown-6 or 18-crown-6, and the cyclic alcohol is cyclopropanol or cyclohexanol; the dosage of the inorganic nitrate is 5-50 mg / L; the dosage of the crown ether is 1-5 mg / L; the dosage of the cyclic alcohol is 1-10 mL / L; and the dosage of the glycolic acid is 5-20 mL / L.

2. A method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation, characterized in that: The electrolytic copper foil is obtained by direct current electrolysis using a copper sulfate + sulfuric acid solution as an electrolyte and inorganic nitrates and organic matter as additives; the inorganic nitrate is one or a combination of ammonium nitrate, copper nitrate, and bismuth nitrate; the organic matter is a crown ether, a cyclic alcohol, and glycolic acid; the crown ether is diaza-18-crown-6 or 18-crown-6, and the cyclic alcohol is cyclopropanol or cyclohexanol; the amount of the inorganic nitrate is 5-50 mg / L; the amount of the crown ether is 1-5 mg / L; the amount of the cyclic alcohol is 1-10 mL / L; and the amount of the glycolic acid is 5-20 mL / L.

3. The method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation according to claim 2, characterized in that: The concentration of copper sulfate in the copper sulfate + sulfuric acid solution is 80-120 g / L, and the concentration of sulfuric acid is 0.3-3 mol / L.

4. The method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation according to claim 2, characterized in that: The current density during electrolysis is 2000~6000A / m 2 .

5. The method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation according to claim 2, characterized in that: The electrolyte temperature during electrolysis is 50~60℃.

6. The method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation according to claim 2, characterized in that: The thickness of the copper foil is controlled by the electrolysis time.

7. The method for preparing an ultra-thin electrolytic copper foil with high tensile strength and high elongation according to claim 2, 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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