Lithium copper foil and its preparation method and application
By using specific solution electrolysis and annealing treatment, combined with the synergistic effect of multiple additives, a high-strength and low-brittle lithium-ion battery copper foil was prepared, which solved the mechanical stress problem of existing copper foil during the expansion process of silicon-based negative electrodes and improved the performance of lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 江西铜博科技股份有限公司
- Filing Date
- 2026-02-12
- Publication Date
- 2026-05-29
AI Technical Summary
Existing high-strength copper foil is brittle and cannot adapt to the volume expansion of silicon-based anodes during charging and discharging, leading to battery cycle life and safety issues.
A high-strength, low-brittle lithium-ion battery copper foil was prepared by mixing a specific ratio of hydrochloric acid, sulfuric acid, and copper sulfate solution with solutions A and B, followed by electrolysis and anti-oxidation treatment and step-by-step annealing. The synergistic effect of sulfonated hydroxyethyl cellulose, modified polyethylene glycol, sodium polydithiopropane sulfonate, tetrahydrothiazole copper sulfate, and small molecule proteins was utilized.
The prepared lithium-ion battery copper foil has a tensile strength exceeding 600 MPa, exhibits no cracks after 180° folding, and has a high-temperature elongation exceeding 4%. It is suitable for silicon-based negative electrode lithium-ion batteries, improving the battery's cycle life and safety.
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Figure CN122105542A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of copper foil preparation technology, and in particular to a lithium-ion battery copper foil, its preparation method, and its application. Background Technology
[0002] With the rapid development of new energy vehicles, energy storage systems, and consumer electronics, the performance requirements for lithium-ion batteries are increasing, especially in terms of energy density, cycle life, and safety. Silicon-based anodes, with a theoretical capacity of 4200 mAh / g (approximately 10 times that of graphite anodes), are considered a core choice for next-generation high-capacity anode materials. However, silicon-based materials experience volume expansion of over 300% during charging and discharging, causing the copper foil current collector in the anode to bear enormous mechanical stress, making it highly susceptible to breakage and failure, severely impacting battery cycle life and safety.
[0003] However, the high-strength copper foil in the existing technology is brittle and cannot adapt to the problem of heat expansion of the negative electrode. Summary of the Invention
[0004] This invention provides a lithium battery copper foil, its preparation method, and its application, which has high tensile strength and low brittleness.
[0005] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a method for preparing lithium battery copper foil, comprising: Step S1: Mix the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B evenly to obtain the electroplating solution; wherein, the mass ratio of the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B is 150,000~200,000:1~3:1~2; solution A is prepared by dissolving sulfonated hydroxyethyl cellulose and modified polyethylene glycol in pure water; solution B is prepared by dissolving sodium polydisulfide dipropane sulfonate, tetrahydrothiazole copper sulfate, and small molecule protein in pure water; the small molecule protein is obtained by enzymatic hydrolysis and purification of fish skin small molecule protein, with a molecular weight of 3000~5000; Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain raw foil; Step S3: The raw foil is subjected to anti-oxidation treatment and annealing treatment to obtain the lithium battery copper foil.
[0006] According to one embodiment of the present invention, in step S1, the concentration of sulfonated hydroxyethyl cellulose is 2.0~3.0 g / L, the concentration of modified polyethylene glycol is 0.5~1.5 g / L, the concentration of sodium polydisulfide dipropane sulfonate is 3.0~4.5 g / L, the concentration of tetrahydrothiazole copper sulfate is 2.5~3.4 g / L, and the concentration of small molecule protein is 1.0~2.0 g / L.
[0007] According to one embodiment of the present invention, in liquid B, the concentration ratio of the small molecule protein to the sodium polydisulfide dipropane sulfonate is 1:2~3.
[0008] According to one embodiment of the present invention, the modified polyethylene glycol is an amino-modified polyethylene glycol with a molecular weight of 8000~12000, and the mass ratio of the modified polyethylene glycol to the sulfonated hydroxyethyl cellulose is 1:1.5~2.0.
[0009] According to one embodiment of the present invention, in the mixed solution of step S1, The mass concentration is 85~95 g / L, and the mass concentration of sulfuric acid is 95~115 g / L. The mass concentration is 25~30 mg / L.
[0010] According to one embodiment of the present invention, in step S2, the electrolysis temperature is 50~55℃, the current density is 4500~6000A / m², the flow rate during the electrolysis process is 50~60m³ / h, and the thickness of the green foil is 6~10μm.
[0011] According to one embodiment of the present invention, in step S3, the annealing process is to anneal at 70~80°C for 12~20h, and then anneal at 90~100°C for 8~16h.
[0012] According to one embodiment of the present invention, in step S3, the anti-oxidation treatment involves immersing the raw foil in an anti-oxidation solution for 3-5 seconds. The anti-oxidation solution is a mixture containing hexavalent chromium ions and phosphate ions, with a pH value of 2.0-2.5 and a temperature of 25-35°C. The concentration of hexavalent chromium ions is 1.2-1.6 g / L, and the concentration of phosphate ions is 1.5-2.0 g / L.
[0013] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: to provide a lithium battery copper foil prepared by the above-mentioned method, wherein the lithium battery copper foil has a tensile strength of more than 600 MPa, no cracks after being folded and rolled by a 2 kg roller at 180° and has a tensile strength of more than 450 MPa, and a high temperature elongation of more than 4%.
[0014] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide an application of the aforementioned lithium-ion battery copper foil in the negative electrode current collector of a lithium-ion battery.
[0015] The beneficial effects of this invention are: the selective adsorption of sulfonated hydroxyethyl cellulose onto the cathode surface refines the copper grain size; modified polyethylene glycol inhibits abnormal grain growth through steric hindrance, forming a uniform and dense coating structure; and sodium polydisulfide dipropane sulfonate promotes… The additives reduce interfacial tension and refine grains; tetrahydrothiazole copper sulfate further refines grains; low molecular weight small molecule proteins fill grain boundary defects and improve grain boundary bonding; through the synergistic effect of the above additives, it is possible to prepare lithium battery copper foil with both high strength and low brittleness, with a tensile strength exceeding 600 MPa, no cracks after being folded and rolled by a 2 kg roller at 180° and a tensile strength exceeding 450 MPa, and a high temperature elongation exceeding 4%. Attached Figure Description
[0016] Figure 1 This is a schematic flowchart of a method for preparing lithium-ion battery copper foil according to an embodiment of the present invention.
[0017] Figure 2 These are XRD patterns of the lithium-ion battery copper foils prepared in Example 1 and Comparative Example 1.
[0018] Figure 3 This is an EBSD effect diagram of the lithium battery copper foil prepared in Example 1.
[0019] Figure 4 This is an EBSD effect diagram of the lithium battery copper foil prepared in Comparative Example 1. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0021] The terms "first," "second," and "third" used in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this invention are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indications also change accordingly. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.
[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0023] Figure 1 This is a schematic flowchart illustrating a method for preparing lithium-ion battery copper foil according to an embodiment of the present invention. It should be noted that if substantially the same result is obtained, the method of the present invention is not necessarily identical. Figure 1 The illustrated process sequence is limited. For example... Figure 1 As shown, the method includes the following steps: Step S1: Mix the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B evenly to obtain the electroplating solution; wherein, the mass ratio of the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B is 150,000~200,000:1~3:1~2; solution A is made by dissolving sulfonated hydroxyethyl cellulose and modified polyethylene glycol in pure water; solution B is made by dissolving sodium polydisulfide dipropane sulfonate, tetrahydrothiazole copper sulfate, and small molecule protein in pure water; the small molecule protein is obtained by enzymatic hydrolysis and purification of small molecule protein from fish skin, with a molecular weight of 3,000~5,000.
[0024] In step S1, in the mixed solution, The mass concentration is 85~95 g / L, and the mass concentration of sulfuric acid is 95~115 g / L. The mass concentration is 25~30 mg / L. Furthermore, in the mixed solution, the content of impurity cations is controlled as follows: ≤1.5mg / L ≤1.0mg / L ≤1.0mg / L ≤3mg / L ≤3 mg / L. The concentrations of sulfonated hydroxyethyl cellulose are 2.0~3.0 g / L, modified polyethylene glycol is 0.5~1.5 g / L, sodium polydisulfide dipropane sulfonate is 3.0~4.5 g / L, tetrahydrothiazole copper sulfate is 2.5~3.4 g / L, and small molecule protein is 1.0~2.0 g / L. In solution B, the concentration ratio of small molecule protein to sodium polydisulfide dipropane sulfonate is 1:2~3. In solution A, the modified polyethylene glycol is amino-modified polyethylene glycol with a molecular weight of 8000~12000, and the mass ratio of modified polyethylene glycol to sulfonated hydroxyethyl cellulose is 1:1.5~2.0.
[0025] Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain raw foil.
[0026] In step S2, the electroplating solution is fed into an electrolytic cell and electrolyzed at an electrolysis temperature of 50-55°C, a current density of 4500-6000 A / m², and a flow rate of 50-60 m³ / h to obtain a green foil with a thickness of 6-10 μm. Preferably, the electrolysis process uses a titanium-based coated cathode roller, with a surface roughness Ra controlled at 0.1-0.3 μm, achieving a combination of ultra-thin thickness (6-10 μm) and low roughness characteristics, adapting to the thin coating requirements of silicon-based anodes, and reducing the interfacial contact resistance by more than 15%.
[0027] Step S3: Perform anti-oxidation treatment and annealing on the raw foil to obtain lithium battery copper foil.
[0028] In step S3, the anti-oxidation treatment involves immersing the raw foil in an anti-oxidation solution for 3-5 seconds. The anti-oxidation solution is a mixture containing hexavalent chromium ions and phosphate ions, with a pH value of 2.0-2.5, a temperature of 25-35°C, a concentration of hexavalent chromium ions of 1.2-1.6 g / L, and a concentration of phosphate ions of 1.5-2.0 g / L.
[0029] Preferably, the annealing process employs a stepped annealing method, including a low-temperature stage (e.g., 70-80°C) and a high-temperature stage (e.g., 90-100°C). The low-temperature stage primarily eliminates internal stress generated during electrolysis, preventing grain coarsening caused by rapid high-temperature annealing. The high-temperature stage promotes atomic diffusion, repairs microscopic defects, and controls the degree of recrystallization, achieving a balance between strength and toughness. This embodiment utilizes a stepped annealing process, which improves strength retention by 10-15% compared to traditional single-temperature annealing.
[0030] Preferably, the annealing process involves annealing at 70-80°C for 12-20 hours, followed by annealing at 90-100°C for 8-16 hours, and then naturally cooling to obtain ultra-high strength and low brittleness lithium-ion battery copper foil. Preferably, the annealing process is carried out under inert gas protection, for example, nitrogen with a purity ≥99.99% and a flow rate of 0.5-1.0 m³ / h.
[0031] In one embodiment of the present invention, a method for preparing lithium-ion battery copper foil involves selectively adsorbing sulfonated hydroxyethyl cellulose onto the cathode surface to refine the copper grain size; modified polyethylene glycol inhibits abnormal grain growth through steric hindrance, forming a uniform and dense coating structure; and sodium polydisulfide dipropane sulfonate promotes… The process involves reducing interfacial tension and refining grain size; tetrahydrothiazole copper sulfate further refines the grain size; low molecular weight small molecule proteins fill grain boundary defects and improve grain boundary bonding; through the synergistic effect of the above additives, it is possible to prepare lithium-ion battery copper foil with both high strength and low brittleness, with a tensile strength exceeding 600 MPa. After being folded and rolled at 180° by a 2 kg roller, there are no cracks and the tensile strength exceeds 450 MPa. This solves the problem of high strength copper foil being brittle and difficult to adapt to the expansion of silicon-based anodes in the existing technology, and is especially suitable for cylindrical lithium-ion batteries with silicon-based anodes.
[0032] Embodiments of the present invention also provide an application of lithium-ion battery copper foil in the negative electrode current collector of lithium-ion batteries. This lithium-ion battery copper foil is particularly suitable for silicon-based cylindrical negative electrode lithium-ion batteries, solving the problem that high-strength copper foil is brittle and difficult to adapt to the expansion of silicon-based negative electrodes.
[0033] Example 1 Step S1: Mix the solutions according to the mass ratio of mixed solution: liquid A: liquid B = 180000:2:1.5 to obtain the electroplating solution; Mixed solution: =92g / L, =105g / L, =30mg / L; Solution A: 2.0 g / L sulfonated hydroxyethyl cellulose + 1.0 g / L amino-modified polyethylene glycol (molecular weight 10000); Solution B: Sodium polydisulfide dipropane sulfonate 4.0 g / L + copper tetrahydrothiazole sulfide 3.0 g / L + small molecule protein (molecular weight 3000) 1.5 g / L; Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain a green foil; the electrolysis temperature is 52℃, the current density is 5000A / m², the flow rate is 55m³ / h, and the thickness of the green foil is 6μm. Step S3: Perform anti-oxidation treatment and annealing on the raw foil to obtain lithium battery copper foil; Antioxidant treatment: hexavalent chromium ions 1.4 g / L, phosphate ions 1.8 g / L, pH=2.2, temperature 30℃, treatment time 4 s; Annealing treatment: first anneal at 80℃ for 18 hours, then anneal at 95℃ for 12 hours under nitrogen protection.
[0034] Example 2 Step S1: Mix the solutions according to the mass ratio of mixed solution: liquid A: liquid B = 150000:1:1 to obtain the electroplating solution; Mixed solution: =92g / L, =105g / L, =30mg / L; Solution A: 2.5 g / L sulfonated hydroxyethyl cellulose + 1.0 g / L amino-modified polyethylene glycol (molecular weight 8000); Solution B: Sodium polydisulfide dipropane sulfonate 4.0 g / L + copper tetrahydrothiazole sulfide 2.5 g / L + small molecule protein (molecular weight 3000) 1.5 g / L; Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain a green foil; the electrolysis temperature is 50℃, the current density is 5500A / m², the flow rate is 60m³ / h, and the thickness of the green foil is 8μm. Step S3: Perform anti-oxidation treatment and annealing on the raw foil to obtain lithium battery copper foil; Antioxidant treatment: hexavalent chromium ions 1.2 g / L, phosphate ions 1.5 g / L, pH=2.0, temperature 25℃, treatment time 3 s; Annealing treatment: first anneal at 80℃ for 20 hours, then anneal at 100℃ for 16 hours under nitrogen protection.
[0035] Example 3 Step S1: Mix the solutions according to the mass ratio of mixed solution: liquid A: liquid B = 200000:3:2 to obtain the electroplating solution; Mixed solution: =95g / L, =115g / L, =30mg / L; Solution A: 3.0 g / L sulfonated hydroxyethyl cellulose + 1.5 g / L amino-modified polyethylene glycol (molecular weight 12000); Solution B: Sodium polydisulfide dipropane sulfonate 4.5 g / L + copper tetrahydrothiazole sulfide 3.4 g / L + small molecule protein (molecular weight 3000) 2.0 g / L; Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain a green foil; the electrolysis temperature is 55℃, the current density is 6000A / m², the flow rate is 60m³ / h, and the thickness of the green foil is 10μm. Step S3: Perform anti-oxidation treatment and annealing on the raw foil to obtain lithium battery copper foil; Antioxidant treatment: hexavalent chromium ions 1.6 g / L, phosphate ions 2.0 g / L, pH=2.5, temperature 35℃, treatment time 5s; Annealing treatment: first anneal at 80℃ for 12 hours, then anneal at 90℃ for 8 hours under nitrogen protection.
[0036] Comparative Example 1 Except that solution A contains only 2.0 g / L of sulfonated hydroxyethyl cellulose, the rest is the same as in Example 1.
[0037] Comparative Example 2 Except for the annealing treatment, which is 80℃×24h, the rest is the same as in Example 1.
[0038] Comparative Example 3 Step S1: Dissolve a clean 8mm copper wire in a copper dissolving tank with concentrated sulfuric acid of 99.95% or higher to obtain a high-concentration copper sulfate solution. The copper sulfate solution in the copper dissolving tank overflows into the sludge tank. After being pumped by the sludge pump, the copper sulfate solution in the sludge tank passes through a micron-level silica filter and a micron-level bag filter into the clean solution tank to obtain a pure electroplating solution. Step S2: Mix sulfonated hydroxyethyl cellulose, polyethylene glycol, octadecylamine polyoxyethylene ether, ethylene thiourea, collagen with a molecular weight of 3000 Da, and pure water to form solution A. The concentration of sulfonated hydroxyethyl cellulose in solution A is 2.6 g / L, the concentration of polyethylene glycol is 1.2 g / L, the concentration of octadecylamine polyoxyethylene ether is 1.6 g / L, the concentration of ethylene thiourea is 4.8 g / L, and the concentration of collagen is 24.0 g / L. Mix isothiourea propanesulfonic acid inner salt, sodium polydithiopropanesulfonate (both added in equal mass) and pure water to obtain solution B. The total concentration of brightener is 2.2 g / L. Add solutions A and B simultaneously to the clean liquid tank at a flow rate of 10 L / h. Step S3: After uniformly mixing solutions A and B with the pure electroplating solution, an electroplating solution is obtained (the concentration of polyol in the electroplating solution is 0.8 g / m³, and the concentration of brightener is 1.5 g / m³). This solution is then fed into the electroplating tank at a temperature of 51°C and a flow rate of 52 m³ / h. The current density is set to 6800 A / dm³. 2 After electroplating deposition on the surface of the cathode roller for about 24 seconds, a semi-finished copper foil is obtained after peeling. Step S4: Mix chromium anhydride, phosphoric acid and pure water to obtain an anti-oxidation solution. The concentration of hexavalent chromium ions in the anti-oxidation solution is 1.2 g / L, the concentration of phosphate ions is 1.3 g / L, the pH value is 1.82, and the temperature is 25℃. The raw foil prepared in step (3) is introduced into the anti-oxidation solution through a guide roller, soaked for 5 seconds and then exported. After removing excess anti-oxidation solution, it is dried and rolled up. Step S5: Anneal the wound copper foil at 80°C for 22 hours to obtain a lithium battery copper foil with a thickness of 8μm.
[0039] test 1. Tensile strength: According to GB / T29847-2013, using an Instron 3365 testing machine, the tensile speed is 50 mm / min.
[0040] 2. Folding test: Using a 2kg rubber-coated steel roller, the tensile strength is tested after folding and rolling the roller once. 3. High-temperature elongation: After heating at 140℃ for 15 minutes, test the tensile strength according to the above-mentioned test method; 4. Surface roughness: Ra value was measured using a white light interferometer.
[0041] The test results of the lithium-ion battery copper foils prepared in each embodiment and comparative example are shown in Table 1.
[0042] Table 1 The XRD patterns of the lithium-ion battery copper foil prepared in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown, Figure 3 and Figure 4 As shown, compared with the grain color of the lithium-ion battery copper foil prepared in Comparative Example 1, the grain color distribution of the lithium-ion battery copper foil prepared in Example 1 is more uniform, and its brittleness is relatively lower; combined with Table 1, Figures 2-4 It can be seen that the tensile strength of Examples 1-3 all exceeded 600 MPa, and no cracks were observed after being folded and rolled by a 2 kg roller. The tensile strength after being folded and rolled by a 2 kg roller at 180° was all above 450 MPa. The elongation was ≥4% after heating at 140°C for 15 min, and the surface roughness Ra ≤ 0.25 μm, indicating that the embodiments of the present invention successfully achieved a combination of high strength and low brittleness. Comparative Example 1, lacking modified polyethylene glycol, showed a decrease in tensile strength to 205 MPa after being folded and rolled by a 2 kg roller at 180°, indicating the importance of the synergistic effect of the additives. Comparative Example 2, without using a stepped annealing process, showed a decrease in tensile strength to 385 MPa after being folded and rolled by a 2 kg roller at 180°, indicating that the stepped annealing process helps to control strength and brittleness. Compared with Comparative Example 3, the embodiments of the present invention showed a 20% increase in tensile strength and solved the problems of bending cracks and large decrease in tensile strength after being folded and rolled by a 2 kg roller.
[0043] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for preparing lithium-ion battery copper foil, characterized in that, include: Step S1: Mix the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B evenly to obtain the electroplating solution; wherein, the mass ratio of the mixed solution containing hydrochloric acid, sulfuric acid, and copper sulfate, solution A, and solution B is 150,000~200,000:1~3:1~2; solution A is prepared by dissolving sulfonated hydroxyethyl cellulose and modified polyethylene glycol in pure water; solution B is prepared by dissolving sodium polydisulfide dipropane sulfonate, tetrahydrothiazole copper sulfate, and small molecule protein in pure water; the small molecule protein is obtained by enzymatic hydrolysis and purification of fish skin small molecule protein, with a molecular weight of 3000~5000; Step S2: The electroplating solution is fed into an electrolytic cell for electrolysis to obtain raw foil; Step S3: Perform anti-oxidation treatment and annealing treatment on the raw foil to obtain the lithium battery copper foil.
2. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, In step S1, the concentration of sulfonated hydroxyethyl cellulose is 2.0~3.0 g / L, the concentration of modified polyethylene glycol is 0.5~1.5 g / L, the concentration of sodium polydisulfide dipropane sulfonate is 3.0~4.5 g / L, the concentration of tetrahydrothiazole copper sulfate is 2.5~3.4 g / L, and the concentration of small molecule protein is 1.0~2.0 g / L.
3. The method for preparing lithium-ion battery copper foil according to claim 2, characterized in that, In solution B, the concentration ratio of the small molecule protein to the sodium polydisulfide dipropane sulfonate is 1:2~3.
4. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, The modified polyethylene glycol is an amino-modified polyethylene glycol with a molecular weight of 8000~12000, and the mass ratio of the modified polyethylene glycol to the sulfonated hydroxyethyl cellulose is 1:1.5~2.
0.
5. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, In the mixed solution of step S1, The mass concentration is 85~95 g / L, and the mass concentration of sulfuric acid is 95~115 g / L. The mass concentration is 25~30 mg / L.
6. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, In step S2, the electrolysis temperature is 50~55℃, the current density is 4500~6000A / m², the flow rate during the electrolysis process is 50~60m³ / h, and the thickness of the green foil is 6~10μm.
7. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, In step S3, the annealing process consists of annealing at 70-80°C for 12-20 hours, followed by annealing at 90-100°C for 8-16 hours.
8. The method for preparing lithium-ion battery copper foil according to claim 1, characterized in that, In step S3, the anti-oxidation treatment involves immersing the raw foil in an anti-oxidation solution for 3-5 seconds. The anti-oxidation solution is a mixture containing hexavalent chromium ions and phosphate ions, with a pH value of 2.0-2.5 and a temperature of 25-35°C. The concentration of hexavalent chromium ions is 1.2-1.6 g / L, and the concentration of phosphate ions is 1.5-2.0 g / L.
9. A lithium-ion battery copper foil prepared by the method for preparing lithium-ion battery copper foil according to any one of claims 1-8, characterized in that, The lithium battery copper foil has a tensile strength exceeding 600 MPa, and after being folded and rolled at 180° by a 2 kg roller, it shows no cracks and a tensile strength exceeding 450 MPa, with a high-temperature elongation exceeding 4%.
10. The application of the lithium-ion battery copper foil as described in claim 9 in the negative electrode current collector of a lithium-ion battery.