Additive for preparing high-strength extremely thin lithium copper foil under high current density and production process

Abstract

The application discloses an additive for preparing high-strength extremely thin lithium battery copper foil under high current density and a production process, and belongs to the technical field of electrolytic copper foil. The additive is prepared by compounding collagen peptide, polydithiodipropyl sulfone sodium, polyethylene glycol-6000, 3-(benzo thiazole-2-methyl) propane sulfonic acid sodium, 2-methyl benzothiazole and hydrochloric acid according to specific contents. The production process comprises the following steps: preparing high-cleanliness copper sulfate electrolyte, mixing the additive with the electrolyte, mixing the additive with the electrolyte under 7000-7500 A / m 2 Electrodeposition foil under high current density. The application uses collagen peptide to replace traditional gelatin, cooperates with sulfur-containing additives and hydrochloric acid, and can significantly improve the tensile strength of copper foil, inhibit apparent defects such as copper powder and burrs, reduce warping and roughness, and can stably produce 4.5-6 mu m high-strength extremely thin lithium battery copper foil, which is suitable for the high energy density demand of power batteries.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic copper foil preparation technology, specifically relating to an additive and production process for preparing high-strength ultra-thin lithium battery copper foil under high current density. Background Technology

[0002] As lithium-ion batteries develop towards thinner, lighter, higher energy density, and longer cycle life, the copper foil for the negative electrode needs to achieve both ultra-thin thickness and high strength. Ultra-thin, high-strength copper foil of 4.5-6μm has become the mainstream demand in the industry.

[0003] The current production of ultra-thin lithium-ion battery copper foil has the following technical defects: 1. Traditional additives use high molecular weight gelatin as a leveling agent, which has poor leveling properties, makes the copper foil easy to warp, and the gelatin residue accumulates in the electrolyte, which can easily disturb the production process. 2. When conventional additive systems are produced under high current density, they are prone to surface defects such as copper powder, burrs, and pinholes, which limits the improvement of tensile strength. 3. Poor adaptability of production process parameters, insufficient production stability under high current density, long warpage aging cycle, low production efficiency, and difficulty in meeting the requirements of mass production.

[0004] Therefore, developing additives and production processes that are suitable for high current densities and can simultaneously improve the mechanical properties and surface quality of copper foil has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the problems of low production efficiency, difficulty in improving strength, severe warping, and frequent surface defects in existing ultra-thin lithium-ion battery copper foil production technology, the purpose of this invention is to provide an additive and production process for preparing high-strength ultra-thin lithium-ion battery copper foil at high current density, achieving stable production at high current density, improving the tensile strength of copper foil, suppressing surface defects, and reducing warping and roughness.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An additive for preparing high-strength, ultra-thin lithium-ion battery copper foil under high current density is disclosed, comprising agent A, agent B, agent C, agent D, agent E, and hydrochloric acid; wherein agent A is collagen peptide, and its content in the electrolyte is 2.2-2.7 g / m³. 3 Agent B is sodium polydisulfide dipropane sulfonate, with a content of 3.0-3.5 g / m³ in the electrolyte. 3 The agent C is polyethylene glycol-6000, and its content in the electrolyte is 0.12-0.185 g / m³. 3 The agent D is sodium 3-(benzothiazol-2-mercapto)-propanesulfonate, with a content of 0.3-0.4 g / m³ in the electrolyte. 3The agent E is 2-mercaptobenzothiazole, with a content of 0.9-1.2 g / m³ in the electrolyte. 3 The hydrochloric acid content in the electrolyte is 26-32 ppm.

[0007] Preferably, a process for preparing a high-strength, ultra-thin lithium-ion battery copper foil, using the additive described in claim 1, includes the following steps: Step 1: Preparation of high-purity copper sulfate electrolyte: Using high-purity cathode copper wire, concentrated sulfuric acid, and pure water as raw materials, copper sulfate solution is prepared through oxidation-reduction reaction under the action of compressed air. After pre-filtration through a diatomaceous earth filter, high-purity copper sulfate electrolyte is obtained. Step 2: Mixing electrolyte and additives: The pre-filtered copper sulfate electrolyte is sequentially fed into the clean liquid tank and the high-level tank. The additive described in claim 1 is prepared into a solution and then pumped into the high-level tank to be fully mixed with the copper sulfate electrolyte to obtain a mixed electrolyte. Step 3: Electrodeposition foil production: The mixed electrolyte is fed into the anode tank of the foil production machine, and DC current is applied to perform electrodeposition to obtain high-strength ultra-thin lithium battery copper foil.

[0008] Preferably, in the high-purity copper sulfate electrolyte of step 1, the copper ion concentration is 95-100 g / L, the sulfuric acid concentration is 115-125 g / L, the number of 0.5 μm solid particles is less than 500 per L, and the hydrochloric acid content is 26-32 ppm.

[0009] Preferably, the temperature of the mixed electrolyte in step 3 when it is fed into the foil-making machine is 56±2℃; the electrolyte flow rate of a single foil-making machine is 55-60m³ / h. 3 / h; The cathode roller current density of the foil-making machine is 7000-7500 A / m 2 .

[0010] Preferably, the thickness of the lithium battery copper foil is 4.5-6μm; after high-temperature aging treatment, the tensile strength is 460-500MPa, the elongation is 6-7%; the warpage before aging treatment is less than 10mm; the surface roughness Ra≤0.150μm, Rz≤1.600μm.

[0011] Compared with the prior art, the present invention has the following advantages: 1. This technology uses collagen peptides with smaller molecular weights, which have better leveling properties than traditional high molecular weight gelatin, have a significant effect on inhibiting copper foil warping, and their residues will not cause disturbance to the process after being enriched in the electrolyte.

[0012] 2. This technology uses sodium 3-(benzothiazole-2-mercapto)-propanesulfonate (ZPS) and 2-mercaptobenzothiazole. When used together, these two substances significantly improve the tensile strength of copper foil. Furthermore, the presence of hydrochloric acid in the additive solution results in a smooth surface and good gloss of the produced lithium-ion battery copper foil.

[0013] 3. The ultra-thin lithium-ion battery copper foil produced by this method can have its roughness Ra effectively controlled below 0.150μm and Rz effectively controlled below 1.600μm. After high-temperature aging treatment, its tensile strength can be controlled at 460-500MPa, its elongation at 6-7%, and its curling before aging treatment is less than 10mm. Detailed Implementation

[0014] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can fully understand the present invention. The raw materials described in the present invention are all commercially available conventional products, and the methods described are conventional methods unless otherwise specified.

[0015] The following basic preparation process is used in all embodiments of the present invention: Step 1: Preparation of high-purity copper sulfate electrolyte. High-purity cathode copper wire, concentrated sulfuric acid, and pure water are used as raw materials. A copper sulfate solution is prepared by oxidation-reduction reaction under compressed air. The copper sulfate solution is then transported to a diatomaceous earth filter for pre-filtration to obtain a high-purity copper sulfate electrolyte. The electrolyte has a copper ion concentration of 98 g / L, a sulfuric acid concentration of 120 g / L, a 0.5 μm solid particle count of 420 particles / L, and a hydrochloric acid content of 28 ppm.

[0016] Step 2: Mixing the electrolyte and additives. The pre-filtered copper sulfate electrolyte is sequentially transferred to the clean liquid tank and the high-level tank. The additive solution prepared according to the ratio is pumped into the high-level tank and thoroughly mixed with the copper sulfate electrolyte to obtain a mixed electrolyte.

[0017] Step 3: Electrodeposition for Foil Production. The mixed electrolyte is fed into the anode tank of the foil production machine, and the electrolyte temperature is controlled at 56℃. The electrolyte flow rate of a single foil production machine is 58m³ / h. 3 / h, the cathode roller current density of the foil-making machine is 7200A / m 2 Direct current is applied to perform electrodeposition to obtain lithium battery copper foil.

[0018] Example 1 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.2 g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.0 g / m 3 Agent C: Polyethylene glycol-6000 0.12g / m 3Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0g / m 3 Agent E: 2-Mercaptobenzothiazole 0g / m 3 The hydrochloric acid content in the electrolyte was controlled at 26 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.186 μm, and a surface roughness Rz of 1.61 μm. After high-temperature aging treatment, the tensile strength was 341 MPa, the elongation was 6.8%, the warpage before aging treatment was 11 mm, the surface gloss was 169 GS (90°), and the copper foil was free of pinholes and burrs.

[0019] Example 2 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.4 g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.2 g / m 3 Agent C: Polyethylene glycol-6000 0.14g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0.3 g / m 3 Agent E: 2-Mercaptobenzothiazole 0g / m 3 The hydrochloric acid content in the electrolyte was controlled at 26 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.171 μm, and a surface roughness Rz of 1.56 μm. After high-temperature aging treatment, the tensile strength was 368 MPa, and the elongation was 5.6%. The warpage before aging treatment was 14 mm. The surface gloss was 125 GS (90°). The copper foil had pinholes and burrs.

[0020] Example 3 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.4 g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.2 g / m 3 Agent C: Polyethylene glycol-6000 0.14g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0g / m 3 Agent E: 2-Mercaptobenzothiazole 0.9 g / m 3 The hydrochloric acid content in the electrolyte was controlled at 28 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.190 μm, and a surface roughness Rz of 1.63 μm. After high-temperature aging treatment, the tensile strength was 349 MPa, the elongation was 6.3%, the warpage before aging treatment was 10 mm, the surface gloss was 109 GS (90°), and the copper foil was free of pinholes and burrs.

[0021] Example 4 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.5g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.3 g / m 3 Agent C: Polyethylene glycol-6000 0.15g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0.32 g / m 3 Agent E: 2-Mercaptobenzothiazole 0g / m 3 The hydrochloric acid content in the electrolyte was controlled at 28 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.170 μm, and a surface roughness Rz of 1.51 μm. After high-temperature aging treatment, the tensile strength was 370 MPa, the elongation was 6.6%, the warpage before aging treatment was 12 mm, the surface gloss was 175 GS (90°), and the copper foil was free of pinholes and had burrs.

[0022] Example 5 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.5g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.3 g / m 3 Agent C: Polyethylene glycol-6000 0.15g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0.32 g / m 3 Agent E: 2-Mercaptobenzothiazole 0.95 g / m 3 The hydrochloric acid content in the electrolyte was controlled at 28 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.152 μm, and a surface roughness Rz of 1.48 μm. After high-temperature aging treatment, the tensile strength was 406 MPa, the elongation was 7.1%, the warpage before aging treatment was 16 mm, the surface gloss was 190 GS (90°), and the copper foil was free of pinholes and burrs.

[0023] Example 6 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.6 g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.4 g / m 3 Agent C: Polyethylene glycol-6000 0.17g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0.34 g / m 3 Agent E: 2-Mercaptobenzothiazole 1.05 g / m 3The hydrochloric acid content in the electrolyte was controlled at 29 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.146 μm, and a surface roughness Rz of 1.46 μm. After high-temperature aging treatment, the tensile strength was 439 MPa, the elongation was 6.9%, the warpage before aging treatment was 14 mm, the surface gloss was 210 GS (90°), and the copper foil was free of pinholes and burrs.

[0024] Example 7 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.7g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.5g / m 3 Agent C: Polyethylene glycol-6000 0.185g / m 3 Agent D: Sodium 3-(benzothiazol-2-mercapto)-propanesulfonate 0.36 g / m 3 Agent E: 2-Mercaptobenzothiazole 1.1 g / m 3 The hydrochloric acid content in the electrolyte was controlled at 30 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.137 μm, and a surface roughness Rz of 1.39 μm. After high-temperature aging treatment, the tensile strength was 460 MPa, the elongation was 6.4%, the warpage before aging treatment was 9 mm, the surface gloss was 240 GS (90°), and the copper foil was free of pinholes and burrs.

[0025] Example 8 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.7g / m³. 3 Agent B: Sodium polydisulfide dipropane sulfonate 3.5g / m 3 Agent C: Polyethylene glycol-6000 0.185g / m 3 Agent D: Sodium 3-(benzothiazol-2-mercapto)-propanesulfonate 0.38 g / m 3 Agent E: 2-Mercaptobenzothiazole 1.15 g / m³ 3 The hydrochloric acid content in the electrolyte was controlled at 31 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.134 μm, and a surface roughness Rz of 1.38 μm. After high-temperature aging treatment, the tensile strength was 486 MPa, the elongation was 6.1%, the warpage before aging treatment was 9 mm, the surface gloss was 236 GS (90°), and the copper foil was free of pinholes and burrs.

[0026] Example 9 Following the basic preparation process described above, the following additive was added to the electrolyte: Agent A, collagen peptides 2.7g / m³. 3Agent B: Sodium polydisulfide dipropane sulfonate 3.5g / m 3 Agent C: Polyethylene glycol-6000 0.185g / m 3 Agent D: Sodium 3-(benzothiazole-2-mercapto)-propanesulfonate 0.4 g / m 3 Agent E: 2-Mercaptobenzothiazole 1.2 g / m 3 The hydrochloric acid content in the electrolyte was controlled at 32 ppm. The resulting lithium-ion battery copper foil had a thickness of 5 μm, a surface roughness Ra of 0.135 μm, and a surface roughness Rz of 1.37 μm. After high-temperature aging treatment, the tensile strength was 500 MPa, the elongation was 6.4%, the warpage before aging treatment was 8 mm, the surface gloss was 238 GS (90°), and the copper foil was free of pinholes and burrs.

[0027] As can be seen from the above embodiments, when the dosage of agent D, sodium 3-(benzothiazole-2-mercapto)-propanesulfonate, and agent E, 2-mercaptobenzothiazole, is lower than the lower limit of the scope defined in this invention, the tensile strength of the copper foil is not significantly improved, and surface defects such as pinholes and burrs are prone to occur. When the dosage of each additive is within the scope defined in this invention, the lithium-ion battery copper foil obtained has the advantages of high strength, low roughness, high gloss, and no surface defects, and can achieve stable batch production under high current density.

Claims

1. An additive for preparing high-strength, ultra-thin lithium-ion battery copper foil at high current density, characterized in that, It consists of agent A, agent B, agent C, agent D, agent E, and hydrochloric acid; agent A is collagen peptide, with a content of 2.2-2.7 g / m³ in the electrolyte. 3 Agent B is sodium polydisulfide dipropane sulfonate, with a content of 3.0-3.5 g / m³ in the electrolyte. 3 The C agent is polyethylene glycol-6000, and its content in the electrolyte is 0.12-0.185 g / m³. 3 The agent D is sodium 3-(benzothiazol-2-mercapto)-propanesulfonate, with a content of 0.3-0.4 g / m³ in the electrolyte. 3 The agent E is 2-mercaptobenzothiazole, with a content of 0.9-1.2 g / m³ in the electrolyte. 3 The hydrochloric acid content in the electrolyte is 26-32 ppm.

2. A process for preparing high-strength, ultra-thin lithium-ion battery copper foil, characterized in that, The use of the additive according to claim 1 includes the following steps: Step 1: Preparation of high-purity copper sulfate electrolyte: Using high-purity cathode copper wire, concentrated sulfuric acid, and pure water as raw materials, copper sulfate solution is prepared through oxidation-reduction reaction under the action of compressed air. After pre-filtration through a diatomaceous earth filter, high-purity copper sulfate electrolyte is obtained. Step 2: Mixing electrolyte and additives: The pre-filtered copper sulfate electrolyte is sequentially fed into the clean liquid tank and the high-level tank. The additive described in claim 1 is prepared into a solution and then pumped into the high-level tank to be fully mixed with the copper sulfate electrolyte to obtain a mixed electrolyte. Step 3: Electrodeposition foil production: The mixed electrolyte is fed into the anode tank of the foil production machine, and DC current is applied to perform electrodeposition to obtain high-strength ultra-thin lithium battery copper foil.

3. The preparation process according to claim 2, characterized in that, In step 1, the high-purity copper sulfate electrolyte has a copper ion concentration of 95-100 g / L, a sulfuric acid concentration of 115-125 g / L, a 0.5 μm solid particle count of less than 500 particles / L, and a hydrochloric acid content of 26-32 ppm.

4. The preparation process according to claim 2, characterized in that, Step 3: The temperature of the mixed electrolyte when it is fed into the foil-making machine is 56±2℃; the electrolyte flow rate of a single foil-making machine is 55-60m³ / h. 3 / h; The cathode roller current density of the foil-making machine is 7000-7500 A / m 2 .

5. The preparation process according to claim 2, characterized in that, The obtained lithium battery copper foil has a thickness of 4.5-6μm; after high-temperature aging treatment, the tensile strength is 460-500MPa and the elongation is 6-7%; the warpage before aging treatment is less than 10mm; the surface roughness Ra≤0.150μm and Rz≤1.600μm.