Electrolytic copper foil chromium-free high-temperature anti-oxidation passivator and preparation method and application thereof

Abstract

The invention provides a chromium-free high-temperature anti-oxidation passivator for electrolytic copper foil, and belongs to the technical field of metal surface treatment. The chromium-free high-temperature anti-oxidation passivator for the electrolytic copper foil takes water as a dispersing agent, and comprises the following components: 3-6g / L of a corrosion inhibitor, 5-20g / L of an antioxidant, 0.2-1g / L of a stabilizer, 0.05-0.5 g / L of a surfactant and a pH regulator, and the pH value of the chromium-free high-temperature anti-oxidation passivator for the electrolytic copper foil is 9-11; wherein the antioxidant comprises phytate, an imidazoline derivative and a nano reinforcing agent in a mass ratio of (2-5): (1-3): (0.1-0.5), through a synergistic mechanism of chemical chelation, physical anchoring, nano filling and oxygen vacancy regulation and control, the high-temperature resistance of the film layer is realized on the premise of no chromium and environmental protection, and a key technical guarantee is provided for manufacturing of the high-performance lithium battery copper foil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal surface treatment, and particularly relates to a chromium-free high-temperature oxidation-resistant passivation agent for electrolytic copper foil and a preparation method and application thereof. BACKGROUND

[0002] In the field of lithium battery copper foil production, although the traditional chromium-containing passivation process can form a dense passivation film on the surface of Cr 3+ and Cr 6+ oxide copper, it faces severe environmental challenges due to the high carcinogenicity of Cr 6+ . Although chromium-free alternative technologies have emerged, existing chromium-free passivation agent formulations still have the following problems: (1) the difference in thermal expansion coefficient between the alloy plating layer and the copper matrix leads to poor film adhesion; (2) copper ion migration above 200 DEG C causes Cu2O / CuO oxidation, resulting in poor high-temperature oxidation resistance.

[0003] The prior art CN116288305A provides a high-temperature oxidation-resistant passivation agent, the passivation film of which can be baked at 180-200 DEG C for 1 hour without discoloration, and the appearance is uniform, but its composition includes benzotriazole (BTA), and the acidic environment also has the risk of damaging the surface oxide layer of the copper foil.

[0004] Therefore, there is an urgent need to develop a chromium-free passivation agent that can simultaneously improve film adhesion and high-temperature oxidation resistance. SUMMARY

[0005] The present application relates to the technical field of metal surface treatment, and particularly relates to a chromium-free high-temperature oxidation-resistant passivation agent for electrolytic copper foil and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a chromium-free high-temperature oxidation-resistant passivation agent for electrolytic copper foil, which comprises the following components:

[0008] water as a dispersant, 3-6 g / L of corrosion inhibitor, 5-20 g / L of antioxidant, 0.2-1 g / L of stabilizer, 0.05-0.5 g / L of surfactant, and pH adjuster;

[0009] The corrosion inhibitor comprises one or more of sodium tungstate, sodium vanadate and sodium silicate;

[0010] The antioxidant comprises phytic acid salt, imidazoline derivative and nano-enhancing agent; the mass ratio among the phytic acid salt, imidazoline derivative and nano-enhancing agent is 2-5:1-3:0.1-0.5.

[0011] The pH of the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil is 9-11.

[0012] Preferably, the phytic acid salt comprises one or more of sodium phytate, potassium phytate and ammonium phytate.

[0013] Preferably, the imidazoline derivative comprises one or more of cocoyl hydroxyethyl imidazoline and 2-phenyl imidazoline.

[0014] Preferably, the nano-enhancing agent comprises one or more of nano-cerium dioxide, nano-titanium dioxide and nano-zinc oxide, and the particle size of the nano-enhancing agent is 10-50 nm.

[0015] Preferably, the stabilizer comprises one or more of polyvinylpyrrolidone and ammonium polyacrylate.

[0016] Preferably, the surfactant comprises one or more of polyethylene glycol octylphenyl ether and fatty alcohol polyoxyethylene ether.

[0017] Preferably, the pH regulator comprises ammonia water, sodium hydroxide or potassium hydroxide.

[0018] The application provides a preparation method of the above-mentioned chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil, comprising the following preparation steps:

[0019] Mixing the nano-enhancing agent with part of water, ultrasonic dispersion, to obtain a nano-enhancing agent dispersion liquid;

[0020] Mixing the corrosion inhibitor with the remaining water, adding the phytic acid salt, imidazoline derivative and nano-enhancing agent dispersion liquid into the obtained corrosion inhibitor solution in sequence, first stirring, to obtain a first intermediate solution;

[0021] Adding the stabilizer and surfactant into the first intermediate solution, second stirring, adding the pH regulator dropwise into the obtained second intermediate solution until the pH is 9-11, to obtain the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil.

[0022] Preferably, the ultrasonic dispersion time is 30-60 min, the power is 200-300 W, and the temperature is 25-30℃.

[0023] The first stirring time is 30-45 min, the rotating speed is 300-500 r / min, and the temperature is 25-30℃.

[0024] The second stirring time is 10-15 min, the rotating speed is 300-350 r / min, and the temperature is 25-30 DEG C.

[0025] The application provides application of the above-mentioned chromium-free high-temperature anti-oxidation passivator for electrolytic copper foil or the chromium-free high-temperature anti-oxidation passivator for electrolytic copper foil prepared by the above-mentioned preparation method to lithium electric copper foil for power batteries, copper foil for energy storage batteries or copper foil for aerospace electronic equipment.

[0026] The application has the following beneficial effects:

[0027] The chromium-free high-temperature anti-oxidation passivator for electrolytic copper foil provided by the application takes corrosion inhibitor and antioxidant as main components, sodium tungstate in the corrosion inhibitor reacts with phytic acid in the antioxidant to generate phosphotungstic heteropoly acid (H3PW 12 O 40 ), which is deposited in the metal lattice defects through interstitial deposition; at the same time, cocoyl hydroxyethyl imidazoline anchors the grain boundary with its long-chain alkyl hydrophobic group to realize surface hydrophobization. The two components synergize to significantly improve the structural stability and high-temperature diffusion barrier performance of the film layer. In addition, the antioxidant realizes the synergistic mechanism of chemical chelation, physical anchoring, nano-filling and oxygen vacancy regulation through the ternary system of phytate / imidazoline derivative / nano CeO2, thereby systematically solving the technical problems of weak film-base bonding force, loose film layer and poor high-temperature oxidation resistance in the traditional passivation process. The phytate is hydrolyzed to generate polyphosphate under alkaline conditions, and a continuous network-like bottom film is formed through crosslinking; the imidazoline derivative mechanically anchors the copper grain boundary through the long-chain alkyl group, thereby significantly enhancing the interface mechanical locking force. In addition, the imidazoline derivative decomposes at high temperature to form a dense carbon nitride barrier, which synergistically inhibits the migration of copper ions; the nano CeO2 undergoes reversible oxidation and reduction (Ce 3+ / Ce 4+ ) above 200 DEG C, thereby continuously eliminating active oxygen free radicals; the phytate-CeO2 composite film layer blocks the conversion path of Cu + to Cu2O / CuO, thereby significantly improving the high-temperature yellowing resistance, and providing key technical support for the manufacture of high-performance lithium electric copper foil. DETAILED DESCRIPTION

[0028] The application provides a chromium-free high-temperature anti-oxidation passivator for electrolytic copper foil, which comprises the following components:

[0029] Water is used as a dispersant, the corrosion inhibitor is 3-6 g / L, the antioxidant is 5-20 g / L, the stabilizer is 0.2-1 g / L, the surfactant is 0.05-0.5 g / L, and the pH regulator is used;

[0030] The corrosion inhibitor comprises one or more of sodium tungstate, sodium vanadate and sodium silicate;

[0031] The antioxidant includes phytic acid salt, imidazoline derivative and nano-enhancing agent; the mass ratio of the phytic acid salt, imidazoline derivative and nano-enhancing agent is 2-5:1-3:0.1-0.5.

[0032] The pH of the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil is 9-11.

[0033] In the present application, if not otherwise specified, the required preparation raw materials are all commercially available goods well known to those skilled in the art.

[0034] The concentration of the corrosion inhibitor in the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil is preferably 3-6 g / L, and further preferably 4-5 g / L; the corrosion inhibitor preferably includes one or more of sodium tungstate, sodium vanadate and sodium silicate, and further preferably sodium tungstate.

[0035] The concentration of the antioxidant in the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil is preferably 5-20 g / L, and further preferably 10.4-16.8 g / L; the antioxidant preferably includes phytic acid salt, imidazoline derivative and nano-enhancing agent.

[0036] In the present application, the mass ratio of the phytic acid salt, imidazoline derivative and nano-enhancing agent is preferably 2-5:1-3:0.1-0.5, and further preferably 3-4:2-3:0.2-0.4.

[0037] In the present application, the phytic acid salt preferably includes one or more of sodium phytate, potassium phytate and ammonium phytate, and further preferably sodium phytate.

[0038] In the present application, the imidazoline derivative preferably includes one or more of cocoyl hydroxyethyl imidazoline and 2-phenyl imidazoline.

[0039] In the present application, the nano-enhancing agent preferably includes one or more of nano cerium dioxide, nano titanium dioxide and nano zinc oxide, and the particle size of the nano-enhancing agent is preferably 10-50 nm, and further preferably 30-50 nm.

[0040] The concentration of the stabilizer in the chromium-free high-temperature oxidation-preventing passivator for electrolytic copper foil is preferably 0.2-1 g / L, and further preferably 0.5-0.8 g / L; the stabilizer preferably includes one or more of polyvinyl pyrrolidone and polyacrylammonium, and further preferably polyacrylammonium; the stabilizer forms a stable coordination bond with the copper surface through carboxyl, and simultaneously reduces the difference in thermal expansion coefficient between the film layer and the substrate, so that the film layer adhesion is greatly improved, and the film layer peeling caused by high-temperature thermal stress is effectively inhibited.

[0041] The electrolytic copper foil chromium-free high-temperature oxidation-preventing passivation agent provided by the application has the following advantages: the concentration of the surfactant is preferably 0.05-0.5 g / L, and further preferably 0.1-0.3 g / L; the surfactant preferably includes one or more of polyethylene glycol octylphenyl ether and fatty alcohol polyoxyethylene ether, and further preferably fatty alcohol polyoxyethylene ether; the surfactant reduces the interfacial tension through the amphiphilic structure, realizes the super-uniform spreading of the passivation agent, and improves the stability of the film structure by cooperating with the dispersion of nano cerium dioxide.

[0042] The electrolytic copper foil chromium-free high-temperature oxidation-preventing agent provided by the application has the following advantages: the pH regulator preferably includes ammonia, sodium hydroxide or potassium hydroxide, and further preferably ammonia; the pH of the electrolytic copper foil chromium-free high-temperature oxidation-preventing passivation agent is preferably 9-11, and further preferably 9.5-10.5.

[0043] The application provides a preparation method of the electrolytic copper foil chromium-free high-temperature oxidation-preventing passivation agent.

[0044] The nano-enhancing agent is mixed with part of the water, and ultrasonic dispersion is performed to obtain a nano-enhancing agent dispersion liquid;

[0045] The corrosion inhibitor is mixed with the remaining water, and the phytate, the imidazoline derivative and the nano-enhancing agent dispersion liquid are sequentially added to the obtained corrosion inhibitor solution, first stirring is performed, and a first intermediate solution is obtained;

[0046] The stabilizer and the surfactant are added to the first intermediate solution, second stirring is performed, ammonia is added dropwise to the obtained second intermediate solution, and the electrolytic copper foil chromium-free high-temperature oxidation-preventing passivation agent is obtained.

[0047] The application preferably uses a formula amount of nano-enhancing agent, adds part of the water, and performs ultrasonic dispersion to form a uniform nano-enhancing agent dispersion liquid; the ultrasonic dispersion time is preferably 30-60 min, and further preferably 30-45 min; the power is preferably 200-300 W, and further preferably 200-250 W; and the temperature is preferably 25-30 DEG C; the nano-enhancing agent is first mixed with water to form a nano-enhancing agent dispersion liquid, so as to prevent the agglomeration of subsequent materials; and the application does not have special limitations on the use amount ratio between the nano-enhancing agent and the water, and only needs to ensure that the nano-enhancing agent is dissolved smoothly.

[0048] The present application preferably mixes the formula amount of corrosion inhibitor with the remaining water, after complete dissolution, sequentially adds phytate, imidazoline derivative and the above-mentioned nano-enhancing agent dispersion to the obtained corrosion inhibitor solution, carries out first stirring, makes the nanoparticles uniformly embedded in the phytate network, and obtains a first intermediate solution; the time of the first stirring is preferably 30-45 min, further preferably 30-35 min, the rotation speed is preferably 300-500 r / min, further preferably 400-500 r / min, and the temperature is preferably 25-30 DEG C; the present application does not have special limitation on the usage ratio between the corrosion inhibitor and water, and complete dissolution of the corrosion inhibitor is ensured.

[0049] The present application preferably adds the formula amount of stabilizer and surfactant to the above-mentioned first intermediate solution, carries out second stirring until complete dissolution, slowly adds ammonia water to the obtained second intermediate solution while stirring, adjusts the solution pH to 9-11, and obtains the chromium-free high-temperature oxidation-preventing passivation agent for electrolytic copper foil; the time of the second stirring is preferably 10-15 min, further preferably 10-12 min, the rotation speed is preferably 300-350 r / min, further preferably 325-350 r / min, and the temperature is preferably 25-30 DEG C; the solution pH is adjusted to 9-11 because the alkaline condition can slightly dissolve the oxide layer on the surface of the copper foil, expose the fresh copper surface, make the passivation agent components quickly adsorb and form a "chelation-coordination" bond.

[0050] The present application preferably uses after room temperature aging for 24 h after adjusting the solution pH to 9-11, and ensures the synergistic stability of the components.

[0051] The present application also provides the application of the above-mentioned chromium-free high-temperature oxidation-preventing passivation agent for electrolytic copper foil or the chromium-free high-temperature oxidation-preventing passivation agent for electrolytic copper foil prepared by the above-mentioned preparation method in lithium electric copper foil for power batteries, copper foil for energy storage batteries or copper foil for aerospace electronic equipment; the application method can be used according to the conventional passivation process, and the application method in the examples is preferably as follows: the electrolytic copper foil is immersed in a 10% sulfuric acid solution, treated at 25-30 DEG C for 10-15 s to remove the Cu2O oxide layer on the surface, and washed with water to remove the surface residual acid; then the immersion type passivation is adopted, the passivation agent temperature is 40-60 DEG C, the treatment time is 30-60 s, and the surface unreacted passivation agent is removed by washing with water; finally, the copper foil is dried in a hot air oven at 60-80 DEG C for 3-5 min, and the dried copper foil is directly wound to avoid secondary pollution.

[0052] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0053] Example 1

[0054] The formula of the chromium-free high-temperature oxidation-preventing passivation agent for electrolytic copper foil provided in the present example is:

[0055] Water as dispersant, sodium tungstate 3.0 g / L, sodium phytate 10.0 g / L, cocoyl hydroxyethyl imidazoline 6.0 g / L, nano cerium dioxide 0.4 g / L, polyacrylamide 0.5 g / L, fatty alcohol polyoxyethylene ether 0.1 g / L; ammonia as pH regulator;

[0056] Mix nano cerium dioxide with part of water, ultrasonic dispersion at 25℃, 300W for 45min to obtain nano cerium dioxide dispersion;

[0057] Mix sodium tungstate with the rest of water, after complete dissolution, add sodium phytate, cocoyl hydroxyethyl imidazoline and the above nano cerium dioxide dispersion in turn, first stirring at 25℃, 400r / min for 35min to obtain first intermediate solution;

[0058] Add polyacrylamide and fatty alcohol polyoxyethylene ether to the obtained first intermediate solution, second stirring at 25℃, 350r / min for 15min, then add ammonia to adjust the pH of the solution to 9.5 to obtain chromium-free high temperature oxidation resistant passivation agent for electrolytic copper foil.

[0059] Example 2

[0060] The difference with Example 1 is only that:

[0061] The formula of the chromium-free high temperature oxidation resistant passivation agent for electrolytic copper foil provided in this example is:

[0062] Water as dispersant, sodium tungstate 5.0 g / L, sodium phytate 8.0 g / L, cocoyl hydroxyethyl imidazoline 6.0 g / L, nano cerium dioxide 0.8 g / L, polyacrylamide 0.8 g / L, fatty alcohol polyoxyethylene ether 0.2 g / L; ammonia as pH regulator.

[0063] Example 3

[0064] The difference with Example 1 is only that:

[0065] The formula of the chromium-free high temperature oxidation resistant passivation agent for electrolytic copper foil provided in this example is:

[0066] Water as dispersant, sodium tungstate 4.0 g / L, sodium phytate 6.0 g / L, cocoyl hydroxyethyl imidazoline 4.0 g / L, nano cerium dioxide 0.4 g / L, polyacrylamide 1.0 g / L, fatty alcohol polyoxyethylene ether 0.3 g / L; ammonia as pH regulator.

[0067] Comparative Example 1

[0068] The difference with Example 1 is only that:

[0069] No sodium phytate is added, and the rest of the components remain unchanged.

[0070] Comparative Example 2

[0071] The difference from Example 1 is only that:

[0072] No cocoxyethyl imidazoline is added, and the rest of the components remain unchanged.

[0073] Comparative Example 3

[0074] The difference from Example 1 is only that:

[0075] No nano cerium dioxide is added, and the rest of the components remain unchanged

[0076] Comparative Example 4

[0077] The difference from Example 1 is only that:

[0078] The ammonium polyacrylate is replaced by gelatin.

[0079] Performance test

[0080] The lithium battery copper foil is immersed in a 10% mass concentration sulfuric acid solution at 30°C for 15 seconds, and the surface residual acid is washed away with water; then the lithium battery copper foil is immersed in the passivation agent obtained in Examples 1-3 and Comparative Examples 1-3 for immersion passivation, the temperature of the passivation agent is 50°C, the treatment time is 45 seconds, and the surface unreacted passivation agent is removed by washing; finally, the lithium battery copper foil is dried in a hot air oven at 70°C for 5 minutes, and the film layer adhesion and high temperature oxidation resistance of the passivation agent are measured by the following method, and the results are recorded in Table 1.

[0081] (1) Film layer adhesion: GB / T 9286-1998, crosshatch method;

[0082] (2) High temperature oxidation resistance: 220°C air oven baking for 1 hour, observing the surface state of the copper foil, and calculating the color difference value ΔE.

[0083] Table 1 Performance test results of the passivation agent obtained in Examples 1-3 and Comparative Examples 1-4

[0084]

[0085]

[0086] From the above examples and comparative examples, it can be seen that the electrolytic copper foil chromium-free high temperature oxidation passivation agent obtained by the formula has high film layer adhesion, the passivation film is dense and stable, the copper foil surface color difference value is small after 220°C air oven baking for 1 hour, the anti-yellowing performance is excellent, and the high temperature oxidation resistance is good, which is beneficial to prolonging the service life of the copper foil.

[0087] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil, characterized in that, Includes the following components: Water is used as a dispersant, and the following components are included: corrosion inhibitor 3–6 g / L, antioxidant 5–20 g / L, stabilizer 0.2–1 g / L, surfactant 0.05–0.5 g / L, and pH adjuster. The corrosion inhibitor includes one or more of sodium tungstate, sodium vanadate, and sodium silicate. The antioxidant comprises phytate, imidazoline derivative, and nano-reinforcing agent; the mass ratio of phytate, imidazoline derivative, and nano-reinforcing agent is 2-5:1-3:0.1-0.

5. The pH of the chromium-free high-temperature anti-oxidation passivating agent for the electrolytic copper foil is 9-11.

2. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The phytate includes one or more of sodium phytate, potassium phytate, and ammonium phytate.

3. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The imidazoline derivatives include one or more of cocoyl hydroxyethyl imidazoline and 2-phenyl imidazoline.

4. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The nano-reinforcing agent includes one or more of nano-cerium dioxide, nano-titanium dioxide, and nano-zinc oxide, and the particle size of the nano-reinforcing agent is 10-50 nm.

5. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The stabilizer includes one or more of polyvinylpyrrolidone and ammonium polyacrylate.

6. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The surfactant includes one or more of polyethylene glycol octylphenyl ether and fatty alcohol polyoxyethylene ether.

7. The chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claim 1, characterized in that, The pH adjuster includes ammonia, sodium hydroxide, or potassium hydroxide.

8. The method for preparing the chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claims 1 to 7, characterized in that, The preparation steps include the following: The nano-reinforcing agent was mixed with some water and ultrasonically dispersed to obtain a nano-reinforcing agent dispersion. The corrosion inhibitor is mixed with the remaining water, and phytate, imidazoline derivative and nano-reinforcing agent dispersion are added sequentially to the obtained corrosion inhibitor solution. The mixture is stirred for the first time to obtain a first intermediate solution. A stabilizer and a surfactant are added to the first intermediate solution, and the mixture is stirred a second time. A pH adjuster is then added dropwise to the resulting second intermediate solution until the pH is 9-11, thus obtaining a chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil.

9. The preparation method according to claim 8, characterized in that, The ultrasonic dispersion time is 30–60 min, the power is 200–300 W, and the temperature is 25–30 °C. The first stirring time is 30-45 min, the rotation speed is 300-500 r / min, and the temperature is 25-30℃; The second stirring time is 10-15 minutes, the rotation speed is 300-350 r / min, and the temperature is 25-30℃.

10. The application of the chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil according to claims 1 to 7 or the chromium-free high-temperature anti-oxidation passivating agent for electrolytic copper foil prepared by the preparation method according to claims 8 to 9 in lithium-ion battery copper foil for power batteries, copper foil for energy storage batteries or copper foil for aerospace electronic equipment.

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