Preparation method of extremely thin copper foil for high-rate charge-discharge lithium battery
By controlling the electrodeposition process through multi-stage pretreatment and functional additives, ultra-thin copper foil with uniform thickness and dense structure was prepared, which solved the problems of insufficient strength and interfacial bonding of traditional ultra-thin copper foil, and improved the high-rate charge and discharge performance and safety of lithium batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG FINE YUAN SCI TECH CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-06-26
AI Technical Summary
Traditional ultra-thin copper foil has low mechanical strength, insufficient interfacial bonding, and is prone to side reactions with electrolyte, leading to battery performance degradation and making it difficult to meet the requirements of high energy density and high-rate charge and discharge.
A multi-stage pretreatment process of micro-etching, acid washing, dual-treatment solution activation, and electrophoretic isolation layer is adopted, combined with the synergistic adsorption of functional additives on the copper foil surface, to regulate the electrodeposition process and form a dense and uniform ultra-thin copper foil structure.
It significantly improves the mechanical strength and interfacial adhesion of ultra-thin copper foil, reduces internal resistance, and enhances the rate performance, cycle life, and safety of lithium batteries.
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrolytic copper foil production technology for lithium batteries, specifically a method for preparing ultra-thin copper foil for high-rate charge / discharge lithium batteries. Background Technology
[0002] With the rapid development of electric vehicles, portable electronic devices, and large-scale energy storage systems, the demand for high-energy-density and high-power-density lithium-ion batteries is increasing. Copper foil, as a key material for the negative electrode current collector in lithium-ion batteries, directly affects the battery's charge / discharge rate, energy density, and cycle life. Traditional electrolytic copper foil is typically thicker than 6μm, making it difficult to meet the requirements of high-energy-density batteries for thinner and lighter designs. Furthermore, ordinary copper foil is prone to problems such as increased internal resistance, severe heat generation, and active material stripping during high-rate charge / discharge processes, leading to battery performance degradation.
[0003] In existing technologies, electrodeposition is the main method for preparing ultrathin copper foil, but this method has the following problems: First, ultrathin copper foil has low mechanical strength and is prone to breakage during subsequent processing and use; second, the interfacial bonding force between the copper foil and the active material is insufficient, affecting electron transport efficiency; third, during high-rate charge and discharge, the copper foil is prone to side reactions with the electrolyte, leading to increased interfacial impedance; in addition, traditional additive systems are difficult to obtain a uniform and dense microstructure under ultrathin deposition conditions, affecting electrochemical performance.
[0004] Based on the above, the present invention provides a method for preparing ultra-thin copper foil for high-rate charge-discharge lithium batteries, so as to solve the technical problems mentioned above! Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing ultra-thin copper foil for high-rate charge-discharge lithium batteries. The prepared ultra-thin copper foil has the characteristics of uniform thickness, dense structure, low internal stress, excellent conductivity and good surface stability. It is suitable for the negative electrode current collector of high-rate charge-discharge lithium batteries and can significantly improve the rate performance, cycle life and safety of the battery.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for preparing ultrathin copper foil for high-rate charge / discharge lithium batteries includes the following steps:
[0008] Step 1: Perform micro-etching and acid pickling on thin copper foil with a thickness of 15-18μm, a length of 3-5cm, and a width of 3-5cm, and then wash it clean with deionized water for later use.
[0009] Step 2: Immerse the thin copper foil treated in Step 1 in a first treatment solution with a concentration of 2-8 g / L and a pH of 3-7, and soak it at 35-55℃ for 50-100 seconds. After soaking, clean the treated thin copper foil with deionized water and immerse it in a second treatment solution for 50-100 seconds. Then take it out and wash it with deionized water. Store the resulting conductive thin copper foil for later use.
[0010] Step 3: An isolation layer with a thickness of 300-500nm is formed on the surface of the conductive thin copper foil using an electrophoresis process. Then, the treated conductive thin copper foil is cleaned and transferred to an electroplating tank for electrodeposition, and an ultra-thin copper foil of 3-6μm is formed on the surface of the isolation layer.
[0011] Step 4: After cleaning the extremely thin copper foil with a thin copper foil deposit on its surface with deionized water, immerse it in a benzotriazole solution with a concentration of 0.1-0.2wt% and a temperature of 20-35℃ for 50-80 seconds.
[0012] Furthermore, the micro-etching solution used in the micro-etching process includes, by weight percentage: 2-6 wt% hydrogen peroxide, 2-8 wt% dilute sulfuric acid, and the remainder is deionized water; and the immersion time of the thin copper foil in the micro-etching solution is 10-25 s, and the temperature of the micro-etching solution is 30-40 ℃.
[0013] Furthermore, the pickling solution used for pickling includes, by weight percentage: 8-15 wt% concentrated hydrochloric acid, with the balance being deionized water; and the thin copper foil is immersed in the pickling solution for 15-35 seconds, with the temperature of the pickling solution being 30-40℃.
[0014] Furthermore, the solvent in the first treatment solution is deionized water, and the solute is any one of thiocyanuric acid, benzotriazole, and mercaptobenzothiazole.
[0015] Furthermore, the solute in the second treatment solution is polyaniline or polythiophene, and the concentration of the solute is 6-10 g / L; the solvent is an aqueous ethanol solution with a volume concentration of 40-70%.
[0016] Furthermore, the electroplating solution used in electrodeposition contains Cu2+ concentrations of 90-110 g / L, sulfuric acid concentrations of 110-130 g / L, Cl- concentrations of 15-20 mg / L, functional additive concentrations of 20-30 mg / L, polyethylene glycol 8000 concentrations of 25-30 mg / L, gelatin concentrations of 10-20 mg / L, and 2-methyl-3-butyn-2-amine concentrations of 8-12 mg / L; and the molecular weight of the gelatin is 10,000-30,000.
[0017] Furthermore, the electrodeposition temperature is 30-50℃, the current density is 20-50A / dm2, the pulse width is 10-20s, the pulse interval is 10-15s, and the pulse current application time is 50-100s.
[0018] Furthermore, the preparation method of the functional additive includes the following steps:
[0019] Step 1: Dissolve sodium methylene dinaphthalene sulfonate completely in deionized water at a mass ratio of 1:1.5-2. Add 30-40% (by mass) of 2-propyn-1-ol and 10-15% (by mass) of 1-methyl-2-pyrrolidone, and stir at 200-300 rpm for 3-5 minutes. Then add 1.2-1.5 times the amount of dispersant for 2-propyn-1-ol, and continue stirring at 100-200 rpm for 30-40 minutes. Store the resulting mixture for later use.
[0020] The second step involves slowly adding 70-80% of the volume of a mixture to a 1.5-2.5 wt% polyacrylic acid aqueous solution while stirring at a speed of 200-400 r / min, completing the addition within 50-80 min; after the addition is complete, continue stirring for 60-100 min to obtain the functional additive.
[0021] Furthermore, the dispersing agent is a compound of sodium dioctyl succinate sulfonate, octylphenol polyoxyethylene ether, and cocoyl alkyl glycoside in a mass ratio of 5-7:2-4:1.
[0022] Furthermore, the electrodeposition solution used during electrophoresis has the following specific composition: 3-8 g / L of organic complex, 10-30 ml / L of ethanol, and the balance being deionized water; the organic complex is selected from any one of zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, nickel phthalocyanine, magnesium phthalocyanine, and manganese phthalocyanine.
[0023] Compared with the prior art, the beneficial effects of the present invention are:
[0024] 1. A multi-stage pretreatment process consisting of "micro-etching-acid washing-dual-treatment solution activation-electrophoretic isolation layer" significantly improves the cleanliness and chemical activity of the ultra-thin copper foil surface. The first treatment solution forms a coordination adsorption layer on the copper surface, and the second treatment solution further forms a conductive polymer interface layer, providing uniform anchoring points for the subsequent electrophoretic isolation layer. The organic complex isolation layer formed by electrophoresis is not only dense and uniform, but also forms a strong chemical / physical bond with both the underlying conductive polymer layer and the upper electrodeposited copper layer, ensuring the integrity of the final 3-3.5μm ultra-thin copper foil structure and strong adhesion to the substrate, effectively preventing peeling or breakage during subsequent processing and use.
[0025] 2. The functional additives prepared in this invention can preferentially adsorb onto highly active sites on the copper deposition surface, inhibiting excessively rapid and disordered grain growth. The added 2-propynyl-1-ol can produce a synergistic adsorption effect, further reducing cathodic polarization and making the adsorption layer more uniform and dense. 1-Methyl-2-pyrrolidone, as a co-solvent and stabilizer, helps the components to be uniformly dispersed and stably exist in the solution.
[0026] Furthermore, during the preparation of the functional additives, the active components are physically encapsulated and bound to the polyacrylic acid polymer chains through the emulsifying and dispersing effect of the dispersing agent. During electrodeposition, this composite structure can dynamically adsorb onto the cathode surface, and the long polyacrylic acid chains provide steric hindrance, synergistically regulating the reduction deposition rate of copper ions and promoting the formation of an equiaxed fine-grained structure. Simultaneously, the composite additives can effectively release the internal stress generated during electrodeposition, preventing micro-cracks or warping of the copper foil.
[0027] Furthermore, the functional additives, along with polyethylene glycol 8000, gelatin, 2-methyl-3-butynedi-2-amine, and chloride ions in the electroplating solution, work together to form a multi-layered, multifunctional additive adsorption film. This film can precisely control the electrocrystallization process of copper, ultimately yielding ultra-thin copper foils with fine grains, dense structure, low internal stress, smooth and flat surface, and good ductility. Their tensile strength and elongation are significantly superior to similar products prepared using traditional methods.
[0028] 3. The ultra-thin copper foil prepared by this invention possesses extremely high purity, excellent conductivity, and ideal surface morphology. Combined with benzotriazole anti-oxidation treatment, it ensures the chemical stability of the copper foil surface during lamination and battery use, reducing interfacial contact resistance. When the ultra-thin copper foil prepared by this invention is used as a negative electrode current collector in lithium-ion batteries, it provides an efficient and stable electron transport channel, significantly reducing polarization during high-rate charge and discharge, minimizing heat generation, and effectively inhibiting the shedding of active material, thereby greatly improving the battery's rate performance, cycle life, and safety. Detailed Implementation
[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.
[0030] Example 1
[0031] A method for preparing ultrathin copper foil for high-rate charge / discharge lithium batteries includes the following steps:
[0032] Step 1: Perform micro-etching and acid pickling on a thin copper foil with a thickness of 15μm, a length of 3cm, and a width of 3cm, then wash it clean with deionized water and set it aside.
[0033] Step 2: Immerse the thin copper foil treated in Step 1 in the first treatment solution with a concentration of 2g / L and a pH of 3 at 35℃ for 100s. After immersion, clean the treated thin copper foil with deionized water and immerse it in the second treatment solution for 50s. Then take it out and wash it with deionized water. Store the obtained conductive thin copper foil for later use.
[0034] The solvent in the first treatment solution is deionized water, and the solute is thiocyanuric acid.
[0035] The solute in the second treatment solution is polyaniline or polythiophene, and the concentration of the solute is 6 g / L; the solvent is an aqueous ethanol solution with a volume concentration of 40%.
[0036] Step 3: An isolation layer with a thickness of 300nm is formed on the surface of the conductive thin copper foil using an electrophoresis process. Then, the treated conductive thin copper foil is cleaned and transferred to an electroplating tank for electrodeposition, and an ultra-thin copper foil of 3μm is formed on the surface of the isolation layer.
[0037] Step 4: After cleaning the ultra-thin copper foil with a thin copper foil deposited on its surface with deionized water, soak it in a benzotriazole solution with a concentration of 0.1wt% and a temperature of 20℃ for 80 seconds to obtain the ultra-thin copper foil for high-rate charge and discharge lithium batteries.
[0038] The micro-etching solution used in the micro-etching process includes, by weight percentage: 2 wt% hydrogen peroxide, 2 wt% dilute sulfuric acid, and the remainder is deionized water; and the immersion time of the thin copper foil in the micro-etching solution is 10 s, and the temperature of the micro-etching solution is 40 ℃.
[0039] The pickling solution used for pickling includes, by weight percentage: 8 wt% concentrated hydrochloric acid, with the balance being deionized water; and the thin copper foil is immersed in the pickling solution for 15 seconds, with the temperature of the pickling solution being 40°C.
[0040] The electroplating solution used for electrodeposition contained Cu2+ at a concentration of 90 g / L, sulfuric acid at a concentration of 110 g / L, Cl- at a concentration of 15 mg / L, functional additives at a concentration of 20 mg / L, polyethylene glycol 8000 at a concentration of 25 mg / L, gelatin at a concentration of 10 mg / L, and 2-methyl-3-butyn-2-amine at a concentration of 8 mg / L; and the molecular weight of the gelatin was 10000.
[0041] The electrodeposition temperature was 30°C, the current density was 20A / dm², the pulse width was 10s, the pulse interval was 10s, and the pulse current application time was 50s.
[0042] The preparation method of the functional additive includes the following steps:
[0043] Step 1: Dissolve sodium methylene dinaphthalene sulfonate completely in deionized water at a mass ratio of 1:1.5. Add 30% by mass of 2-propyn-1-ol and 10% by mass of 1-methyl-2-pyrrolidone, and stir at 200 rpm for 5 min. Then add 1.2 times the amount of dispersant of 2-propyn-1-ol and continue stirring at 100 rpm for 40 min. Store the resulting mixture for later use.
[0044] The dispersing agent is composed of sodium dioctyl succinate sulfonate, octylphenol polyoxyethylene ether, and cocoyl alkyl glycoside in a mass ratio of 5:2:1.
[0045] The second step involves slowly adding 70% of the volume of a mixture to a 1.5wt% polyacrylic acid aqueous solution while stirring at a speed of 200r / min, completing the addition within 50min; after the addition is complete, continue stirring for 60min to obtain the functional additive.
[0046] The electrodeposition solution used in electrophoresis has the following composition: 3 g / L of organic complex, 10 ml / L of ethanol, and the remainder is deionized water; the organic complex is zinc phthalocyanine.
[0047] Example 2
[0048] A method for preparing ultrathin copper foil for high-rate charge / discharge lithium batteries includes the following steps:
[0049] Step 1: Perform micro-etching and acid pickling on a thin copper foil with a thickness of 15μm, a length of 4cm, and a width of 4cm, then wash it clean with deionized water and set it aside.
[0050] Step 2: Immerse the thin copper foil treated in Step 1 in the first treatment solution with a concentration of 6 g / L and a pH of 5 at 45°C for 80 seconds. After immersion, clean the treated thin copper foil with deionized water and immerse it in the second treatment solution for 70 seconds. Then remove it and wash it with deionized water. Store the obtained conductive thin copper foil for later use.
[0051] The solvent in the first treatment solution is deionized water, and the solute is benzotriazole;
[0052] The solute in the second treatment solution is polyaniline or polythiophene, and the concentration of the solute is 8 g / L; the solvent is an aqueous ethanol solution with a volume concentration of 60%.
[0053] Step 3: An isolation layer with a thickness of 400nm is formed on the surface of the conductive thin copper foil using an electrophoresis process. Then, the treated conductive thin copper foil is cleaned and transferred to an electroplating tank for electrodeposition, and a thin copper foil of 5μm is formed on the surface of the isolation layer.
[0054] Step 4: After cleaning the ultra-thin copper foil with a thin copper foil deposited on its surface with deionized water, immerse it in a benzotriazole solution with a concentration of 0.1 wt% and a temperature of 30°C for 60 seconds to obtain the ultra-thin copper foil for high-rate charge and discharge lithium batteries.
[0055] The micro-etching solution used in the micro-etching process includes, by weight percentage: 4 wt% hydrogen peroxide, 5 wt% dilute sulfuric acid, and the remainder is deionized water; and the immersion time of the thin copper foil in the micro-etching solution is 20 s, and the temperature of the micro-etching solution is 35 ℃.
[0056] The pickling solution used for pickling includes, by weight percentage: 12wt% concentrated hydrochloric acid, with the balance being deionized water; and the thin copper foil is immersed in the pickling solution for 25 seconds, with the temperature of the pickling solution being 35℃.
[0057] The electroplating solution used in electrodeposition contained Cu2+ concentrations of 100 g / L, sulfuric acid concentrations of 120 g / L, Cl- concentrations of 15 mg / L, functional additive concentrations of 25 mg / L, polyethylene glycol 8000 concentrations of 25 mg / L, gelatin concentrations of 15 mg / L, and 2-methyl-3-butyn-2-amine concentrations of 10 mg / L; and the molecular weight of the gelatin was 20,000.
[0058] The electrodeposition temperature was 40°C, the current density was 30A / dm², the pulse width was 15s, the pulse interval was 10s, and the pulse current application time was 80s.
[0059] The preparation method of the functional additive includes the following steps:
[0060] Step 1: Dissolve sodium methylene dinaphthalene sulfonate completely in deionized water at a mass ratio of 1:1.5. Add 35% (by mass) of 2-propyn-1-ol and 10% (by mass) of 1-methyl-2-pyrrolidone, and stir at 250 rpm for 4 min. Then add 1.2 times the amount of dispersant to 2-propyn-1-ol and continue stirring at 150 rpm for 35 min. Store the resulting mixture for later use.
[0061] The dispersing agent is composed of sodium dioctyl succinate sulfonate, octylphenol polyoxyethylene ether, and cocoyl alkyl glycoside in a mass ratio of 6:3:1.
[0062] The second step involves slowly adding 75% of the volume of a mixture to a 2wt% polyacrylic acid aqueous solution while stirring at 300 rpm, completing the addition within 60 minutes. After the addition is complete, continue stirring for another 80 minutes to obtain the functional additive.
[0063] The electrodeposition solution used in electrophoresis has the following composition: 5 g / L of organic complex, 20 ml / L of ethanol, and the remainder is deionized water; the organic complex is tin phthalocyanine.
[0064] Example 3
[0065] A method for preparing ultrathin copper foil for high-rate charge / discharge lithium batteries includes the following steps:
[0066] Step 1: Perform micro-etching and acid pickling on a thin copper foil with a thickness of 18μm, a length of 5cm, and a width of 5cm, then wash it clean with deionized water and set it aside.
[0067] Step 2: Immerse the thin copper foil treated in Step 1 in the first treatment solution with a concentration of 8 g / L and a pH of 7 at 55°C for 50 seconds. After immersion, clean the treated thin copper foil with deionized water and immerse it in the second treatment solution for 100 seconds. Then remove it and wash it with deionized water. Store the resulting conductive thin copper foil for later use.
[0068] The solvent in the first treatment solution is deionized water, and the solute is mercaptobenzothiazole;
[0069] The solute in the second treatment solution is polyaniline or polythiophene, and the concentration of the solute is 10 g / L; the solvent is an aqueous ethanol solution with a volume concentration of 70%.
[0070] Step 3: An isolation layer with a thickness of 500nm is formed on the surface of the conductive thin copper foil using an electrophoresis process. Then, the treated conductive thin copper foil is cleaned and transferred to an electroplating tank for electrodeposition, and a 6μm thin copper foil is formed on the surface of the isolation layer.
[0071] Step 4: After cleaning the ultra-thin copper foil with a thin copper foil deposited on its surface with deionized water, immerse it in a benzotriazole solution with a concentration of 0.2wt% and a temperature of 35℃ for 50 seconds to obtain the ultra-thin copper foil for high-rate charge and discharge lithium batteries.
[0072] The micro-etching solution used in the micro-etching process includes, by weight percentage: 6 wt% hydrogen peroxide, 8 wt% dilute sulfuric acid, and the remainder is deionized water; and the immersion time of the thin copper foil in the micro-etching solution is 25 s, and the temperature of the micro-etching solution is 40 ℃.
[0073] The pickling solution used for pickling includes, by weight percentage: 15wt% concentrated hydrochloric acid, with the balance being deionized water; and the thin copper foil is immersed in the pickling solution for 35 seconds, with the temperature of the pickling solution being 40℃.
[0074] The electroplating solution used in electrodeposition contained Cu2+ concentration of 110 g / L, sulfuric acid concentration of 130 g / L, Cl- concentration of 20 mg / L, functional additive concentration of 30 mg / L, polyethylene glycol 8000 concentration of 30 mg / L, gelatin concentration of 20 mg / L, and 2-methyl-3-butyn-2-amine concentration of 12 mg / L; and the molecular weight of the gelatin was 30,000.
[0075] The electrodeposition temperature was 50°C, the current density was 50A / dm², the pulse width was 20s, the pulse interval was 15s, and the pulse current application time was 100s.
[0076] The preparation method of the functional additive includes the following steps:
[0077] Step 1: Dissolve sodium methylene dinaphthalene sulfonate completely in deionized water at a mass ratio of 1:2. Add 40% (by mass) of 2-propyn-1-ol and 15% (by mass) of 1-methyl-2-pyrrolidone, and stir at 300 rpm for 3 min. Then add 1.5 times the amount of dispersant to 2-propyn-1-ol and continue stirring at 200 rpm for 30 min. Store the resulting mixture for later use.
[0078] The dispersing agent is composed of sodium dioctyl succinate sulfonate, octylphenol polyoxyethylene ether, and cocoyl alkyl glycoside in a mass ratio of 7:4:1.
[0079] The second step involves slowly adding 80% of the volume of a mixture to a 2.5wt% polyacrylic acid aqueous solution while stirring at 400r / min, completing the addition within 80min. After the addition is complete, continue stirring for 100min to obtain the functional additive.
[0080] The electrodeposition solution used in electrophoresis has the following composition: 8 g / L of organic complex, 30 ml / L of ethanol, and the remainder is deionized water; the organic complex is nickel phthalocyanine.
[0081] Comparative Example: The difference from Example 1 is that no functional additives were used in this comparative example.
[0082] Performance testing: The relevant properties of the ultrathin copper foil samples provided in Examples 1-3 and Comparative Example 1 were tested respectively, and the test data are recorded in the table below:
[0083] Test Project Example 1 Example 2 Example 3 Comparative Example Surface roughness (Ra) / μm 0.23 0.28 0.33 0.42 Gloss (60°) / GU 275 255 235 580 Tensile strength / MPa 385 368 352 275 Elongation / % 8.5 9.2 10.5 3.8 Bending radius (from 180° bend to breakage) / mm 1.4 2.3 2.8 5.2 Volume resistivity / μΩ·cm 1.72 1.73 1.74 2.05 5C charging capacity retention rate (compared to 0.2C discharging capacity) / % 91.5 92.2 93.0 75.0 5C discharge capacity retention (compared to 0.2C discharge capacity) / % 90.8 91.5 92.3 73.5 Capacity retention after 500 cycles at 1C (compared to 0.2C discharge capacity) / % 87.5 88.2 89.0 71.5
[0084] By comparing and analyzing the relevant data in the table, it can be seen that the ultra-thin copper foil prepared by this invention has the characteristics of uniform thickness, dense structure, low internal stress, strong adhesion, excellent conductivity, and good surface stability. It is suitable as a negative electrode current collector for high-rate charge-discharge lithium batteries, and can significantly improve the battery's rate performance, cycle life, and safety. This indicates that the method for preparing ultra-thin copper foil for high-rate charge-discharge lithium batteries provided by this invention has a broader market prospect and is more suitable for widespread application.
[0085] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0086] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A method for preparing ultra-thin copper foil for high-rate charge / discharge lithium batteries, characterized in that, Includes the following steps: Step 1: Perform micro-etching and acid pickling on thin copper foil with a thickness of 15-18μm, a length of 3-5cm, and a width of 3-5cm, then wash it clean with deionized water and set it aside. Step 2: Immerse the thin copper foil treated in Step 1 in a first treatment solution with a concentration of 2-8 g / L and a pH of 3-7, and soak it at 35-55℃ for 50-100 seconds. After soaking, clean the treated thin copper foil with deionized water and immerse it in a second treatment solution for 50-100 seconds. Then take it out and wash it with deionized water. Store the resulting conductive thin copper foil for later use. Step 3: An isolation layer with a thickness of 300-500nm is formed on the surface of the conductive thin copper foil using an electrophoresis process. Then, the treated conductive thin copper foil is cleaned and transferred to an electroplating tank for electrodeposition, and an ultra-thin copper foil of 3-6μm is formed on the surface of the isolation layer. Step 4: After cleaning the extremely thin copper foil with a thin copper foil deposit on its surface with deionized water, immerse it in a benzotriazole solution with a concentration of 0.1-0.2wt% and a temperature of 20-35℃ for 50-80 seconds.
2. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that, The micro-etching solution used in the micro-etching process includes, by weight percentage: 2-6 wt% hydrogen peroxide, 2-8 wt% dilute sulfuric acid, and the balance being deionized water; and the immersion time of the thin copper foil in the micro-etching solution is 10-25 s, and the temperature of the micro-etching solution is 30-40 ℃.
3. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that, The pickling solution used for pickling includes, by weight percentage: 8-15 wt% concentrated hydrochloric acid, with the balance being deionized water; and the thin copper foil is immersed in the pickling solution for 15-35 seconds, with the temperature of the pickling solution being 30-40℃.
4. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that: The solvent in the first treatment solution is deionized water, and the solute is any one of thiocyanuric acid, benzotriazole, and mercaptobenzothiazole.
5. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that: The solute in the second treatment solution is polyaniline or polythiophene, and the concentration of the solute is 6-10 g / L; the solvent is an aqueous ethanol solution with a volume concentration of 40-70%.
6. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that, Cu in the electroplating solution used during electrodeposition 2+ The concentration of [unspecified substance] is 90-110 g / L, the concentration of sulfuric acid is 110-130 g / L, and the concentration of Cl [unspecified substance] is [unspecified substance]. - The concentrations of the active ingredient are 15-20 mg / L, the concentrations of the functional additives are 20-30 mg / L, the concentrations of polyethylene glycol 8000 are 25-30 mg / L, the concentrations of gelatin are 10-20 mg / L, and the concentrations of 2-methyl-3-butyn-2-amine are 8-12 mg / L; and the molecular weight of the gelatin is 10,000-30,000.
7. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that: The electrodeposition temperature is 30-50℃, and the current density is 20-50 A / dm³. 2 The pulse width is 10-20s, the pulse interval is 10-15s, and the pulse current application time is 50-100s.
8. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 6, characterized in that, The preparation method of the functional additive includes the following steps: Step 1: Dissolve sodium methylene dinaphthalene sulfonate completely in deionized water at a mass ratio of 1:1.5-2. Add 30-40% (by mass) of 2-propyn-1-ol and 10-15% (by mass) of 1-methyl-2-pyrrolidone, and stir at 200-300 rpm for 3-5 minutes. Then add 1.2-1.5 times the amount of dispersant for 2-propyn-1-ol, and continue stirring at 100-200 rpm for 30-40 minutes. Store the resulting mixture for later use. The second step involves slowly adding 70-80% of the volume of a mixture to a 1.5-2.5 wt% polyacrylic acid aqueous solution while stirring at a speed of 200-400 r / min, completing the addition within 50-80 min; after the addition is complete, continue stirring for 60-100 min to obtain the functional additive.
9. The method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 8, characterized in that: The dispersing agent is a compound of sodium dioctyl succinate sulfonate, octylphenol polyoxyethylene ether, and cocoyl alkyl glycoside in a mass ratio of 5-7:2-4:
1.
10. A method for preparing an ultra-thin copper foil for a high-rate charge / discharge lithium battery according to claim 1, characterized in that, The electrodeposition solution used in electrophoresis has the following specific composition: 3-8 g / L of organic complex, 10-30 ml / L of ethanol, and the balance being deionized water; the organic complex is selected from any one of zinc phthalocyanine, tin phthalocyanine, iron phthalocyanine, nickel phthalocyanine, magnesium phthalocyanine, and manganese phthalocyanine.