Water-based carbon-coated aluminum foil coating and preparation method thereof

Abstract

The invention discloses a water-based carbon aluminum foil coating and a preparation method thereof, and relates to the technical field of carbon aluminum foil coatings. The preparation method comprises the following steps: reacting poly (1, 4-butanediol adipate), isophorone diisocyanate and dimethylolpropionic acid to obtain a polyurethane prepolymer, neutralizing with triethylamine, and emulsifying to prepare a polyurethane pre-emulsion; aniline, pyrrole, p-benzene disulfonic acid and ammonium persulfate are added into the polyurethane emulsion for polymerization, and an aniline-pyrrole copolymer / polyurethane composite emulsion is obtained; performing mixed acid treatment on the superconductive carbon black to obtain oxidized superconductive carbon black; the preparation method comprises the following steps: mixing graphene oxide, oxidized superconductive carbon black and aniline, adding ammonium persulfate for polymerization, and performing hydrazine hydrate hydrothermal reduction to obtain polyaniline grafted reduced graphene oxide / superconductive carbon black composite conductive slurry; and mixing the composite emulsion and the composite conductive slurry with a defoaming agent and a flatting agent, stirring, standing and curing to obtain the coating. The water-based carbon-coated aluminum foil coating prepared by the invention has excellent conductivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon-coated aluminum foil coating, in particular to a water-based carbon-coated aluminum foil coating and a preparation method thereof. BACKGROUND

[0002] Carbon-coated aluminum foil coating is a kind of functional coating material specially used for surface modification of aluminum foil, which is widely used in the field of electronic components such as lithium ion batteries and supercapacitors. Its core function is to form a conductive coating on the surface of the aluminum foil substrate, which can reduce the contact resistance between the electrode and the current collector, improve the electron transmission efficiency, enhance the stability of the active material and the aluminum foil, reduce the interface loss during charging and discharging, and ultimately improve the cycle life and energy density of the device. It is one of the indispensable key materials in the current electronic energy storage field.

[0003] With the improvement of global environmental awareness and the gradual tightening of relevant regulations, the coating industry is accelerating the transformation towards low volatile organic compounds and low pollution. Water-based carbon-coated aluminum foil coating, which uses water as the dispersion medium, has the advantages of environmental protection, safety and convenient construction, gradually replacing traditional oil-based coatings and becoming the mainstream trend in the industry. Among them, water-based carbon-coated aluminum foil coating based on water-based resin has become a key research direction in this field due to its good film-forming property, weather resistance and compatibility with aluminum foil.

[0004] However, the current water-based carbon-coated aluminum foil coating on the market still has obvious shortcomings in terms of conductive performance, which cannot meet the needs of high-end application scenarios such as high-rate charging and discharging batteries. The coating formed by the existing water-based carbon-coated aluminum foil coating has a generally low conductive efficiency, which cannot effectively build a stable and efficient electron transmission path, resulting in problems such as high interface resistance and large electron transmission loss in the actual application of carbon-coated aluminum foil using this coating, which directly restricts the further improvement of the performance of downstream electronic components. How to improve the conductive performance of water-based coatings while maintaining their environmental advantages has become a core problem that needs to be solved in the process of research and application of water-based carbon-coated aluminum foil coating. SUMMARY

[0005] The present application aims to provide a water-based carbon-coated aluminum foil coating and a preparation method thereof to solve the technical problem of poor conductive performance of water-based carbon-coated aluminum foil coating as described in the background. The water-based carbon-coated aluminum foil coating prepared by the present application has excellent conductive performance.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A preparation method of a water-based carbon-coated aluminum foil coating, comprising the following steps: S1, reacting poly-1,4-butanediol adipate diol, isophorone diisocyanate and dimethylol propionic acid to obtain polyurethane prepolymer with isocyanate group at the end, then adding triethylamine for neutralization, and emulsifying in the presence of water to obtain polyurethane pre-emulsion; S2, adding aniline monomer, pyrrole monomer, p-benzenedisulfonic acid and ammonium persulfate into the polyurethane pre-emulsion for polymerization to obtain aniline-pyrrole copolymer / polyurethane composite emulsion; S3, treating superconducting carbon black with mixed acid of concentrated nitric acid and concentrated sulfuric acid to obtain oxidized superconducting carbon black; S4, mixing graphene oxide, oxidized superconducting carbon black and aniline monomer, then adding ammonium persulfate for polymerization to obtain polyaniline grafted graphene oxide / oxidized superconducting carbon black slurry, and performing hydrothermal reduction reaction of the slurry with hydrazine hydrate to obtain polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry; S5, mixing the aniline-pyrrole copolymer / polyurethane composite emulsion, the polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry, silicone defoaming agent and polyether modified siloxane leveling agent, stirring and then standing for curing to obtain water-based carbon-coated aluminum foil paint.

[0007] In the technical scheme of the present application, the conductive performance of the water-based carbon-coated aluminum foil paint is improved from two aspects. On the one hand, the water-based polyurethane binder is modified. The intrinsic insulating property of the water-based polyurethane binder changes it from an insulating barrier to an effective component of the conductive network. Traditional water-based polyurethane is an excellent insulator, which will wrap the conductive filler in the coating and hinder the electron path. The present technology makes aniline and pyrrole copolymerize in situ in the polyurethane colloid particles and on the surface to form an interpenetrating network structure of conductive polyaniline-pyrrole copolymer and polyurethane molecules, and through the double doping effect (the dopant is protonated and doped into the conductive polymer chain, and the sulfonate ion is anchored in the matrix through the interaction with the polyurethane segment), it is ensured that the charge can not only be transmitted along the conductive polymer chain quickly, but also be migrated efficiently in the polyurethane phase through the interface hopping conduction mechanism. In this way, the modified polyurethane binder itself constitutes a continuous conductive phase, which works with the conductive carbon material added subsequently to realize the matrix conductive and significantly reduce the volume resistance of the entire coating system.

[0008] On the other hand, the conductivity of the coating is synergistically improved by doping the binder with a composite conductive paste. Specifically, the acid oxidation treatment of superconducting carbon black first introduces polar functional groups, improving dispersibility and providing active sites for subsequent reactions. In-situ polymerization of polyaniline on the surfaces of graphene oxide and superconducting carbon black oxide allows the polyaniline molecular chains to act as "molecular wires" and "bridges," firmly connecting zero-dimensional carbon black particles to two-dimensional graphene oxide sheets through covalent bonds and strong π-π conjugation. The subsequent hydrothermal reduction process restores the insulating graphene oxide to highly conductive reduced graphene oxide, while the polyaniline is further doped to optimize its conductivity. The final structure consists of superconducting carbon black as dense "point"-like conductive centers, reduced graphene oxide as a large-area "surface" conductive pathway, and polyaniline as a highly efficient "bridging agent." The synergistic effect of these three components significantly increases the conductive contact area and reduces the contact resistance between particles, thus constructing an ultra-high conductivity network far exceeding what can be achieved through physical mixing methods. Figure 1 The image shows an SEM image of the surface of the water-based carbon-coated aluminum foil coating prepared according to this invention after coating the aluminum foil. The SEM image reveals a rough surface structure. This invention achieves excellent electrical conductivity in the water-based carbon-coated aluminum foil coating through the synergistic effect of the two aspects mentioned above.

[0009] Preferably, in step S1, the mass ratio of poly(1,4-butanediol adipate) to isophorone diisocyanate is 5:3 to 4.

[0010] Preferably, in step S1, the amount of dimethylolpropionic acid added is 10 to 20 wt% of the mass of poly(1,4-butanediol adipate).

[0011] Preferably, in step S2, the mass ratio of aniline monomer to pyrrole monomer is 2:0.5 to 1.0.

[0012] Preferably, in step S2, the mass ratio of aniline monomer to terephthalic acid is 1:2 to 3.

[0013] Preferably, in step S4, the mass ratio of graphene oxide, superconducting carbon black oxide, and aniline monomer is 1:3-4:2-3.

[0014] Preferably, in step S4, the polymerization reaction temperature is 0–5°C and the polymerization reaction time is 8–10 h.

[0015] Preferably, in step S5, the polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive paste undergoes pretreatment, including the following steps: Take polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry, adjust the pH to 4-5, then add p-aminobenzenesulfonic acid, sodium nitrite and dilute hydrochloric acid, and react to obtain the final product.

[0016] In the technical solution of this invention, the inventive team discovered through in-depth research that although the above two aspects synergistically endow waterborne polyurethane with excellent intrinsic conductivity and construct an efficient three-dimensional network of carbon material, a further problem encountered when the two are finally compounded is that there is a thermodynamic incompatibility between the hydrophilicity of the modified polyurethane emulsion particle surface and the increased hydrophobicity of the carbon material surface after deep reduction. This results in insufficient bonding between the two phases, which easily leads to uneven micro-dispersion and interface defects, thus forming a pseudo-continuous conductive network with high electron transport impedance, which seriously restricts the full realization of the synergistic effect. To further address this technical problem, our team further modified the conductive carbon material with surface sulfonation. We utilized the reaction of p-aminobenzenesulfonic acid with sodium nitrite under acidic low-temperature conditions to generate a diazonium salt. Subsequently, the diazonium salt underwent an electrophilic substitution coupling reaction with the polyaniline chains and graphene defect sites on the carbon material surface, covalently grafting highly hydrophilic sulfonic acid groups onto the carbon material surface. This modification not only significantly enhanced the dispersion stability of the carbon material in the aqueous phase, but also allowed the sulfonate ions formed after the sulfonic acid groups ionized to form a strong "ion bridge" crosslinking effect with the carboxylate ions on the polyurethane phase surface through the introduction of trace amounts of polyvalent cations. This actively and firmly brought the two-phase interface closer, greatly reducing the interfacial contact resistance and further improving the conductivity of the system.

[0017] Preferably, the amount of p-aminobenzenesulfonic acid added is 0.1 to 0.5 wt% of the polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste.

[0018] A water-based carbon-coated aluminum foil coating is prepared by the above method.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. By transforming the insulating polyurethane adhesive into an intrinsically conductive matrix to form the first conductive phase, a three-dimensional, highly efficient second conductive network is also constructed, with polyaniline as a bridge, superconducting carbon black as points, and reduced graphene oxide as a surface. The synergistic effect of the two fundamentally solves the problem of high resistance in water-based coatings, and the conductivity far exceeds that of simple physical blending systems.

[0020] 2. To address the technical challenge of defects easily occurring at the interface between modified polyurethane and conductive carbon materials, this invention adds surface sulfonation modification to the carbon material. By covalently grafting sulfonic acid groups and introducing an "ion bridge" mechanism, the interfacial bonding between the conductive filler and the polymer matrix is ​​actively strengthened, significantly reducing the interfacial contact resistance and ensuring the continuity and stability of the conductive network. Attached Figure Description

[0021] Figure 1 SEM image of the surface of the coating after the water-based carbon-coated aluminum foil coating prepared in this invention is applied to the aluminum foil. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0023] Example 1 A method for preparing a water-based carbon-coated aluminum foil coating includes the following steps: Step 1: Add 50.0g of poly(1,4-butanediol adipate) diol (molecular weight 2000), 38g of isophorone diisocyanate, and 9g of dimethylolpropionic acid to a four-necked flask. Under nitrogen protection, react in an oil bath at 85°C for approximately 2.5 hours to obtain a polyurethane prepolymer with isocyanate end groups. Cool the system to 45°C, add 5.6g of triethylamine to neutralize the reaction for 30 minutes. Under high-speed shear at 8000 rpm, slowly pour the prepolymer into 400mL of deionized water and emulsify for 30 minutes to obtain a milky white polyurethane preemulsion.

[0024] Step 2: Add 2.0g aniline monomer, 0.8g pyrrole monomer, and 5.5g terephthalic acid sequentially to the polyurethane pre-emulsion, and stir at room temperature for 1 hour to ensure homogeneity. Then, place the reaction system in an ice-water bath at 2°C, and slowly add 50mL of an aqueous solution containing 5.5g ammonium persulfate dropwise while continuously stirring. After the addition is complete, continue the reaction at this low temperature for 10 hours to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion.

[0025] Step 3: Add 5.0 g of superconducting carbon black to a mixed acid solution consisting of 60 mL of concentrated nitric acid and 180 mL of concentrated sulfuric acid. Reflux the mixture at 70 °C and stir for 5 h. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water through vacuum filtration until the filtrate is neutral. Dry the resulting solid in a vacuum drying oven at 80 °C for 12 h to obtain oxidized superconducting carbon black.

[0026] Step 4: Take 250 mL of a 2 mg / mL aqueous dispersion of graphene oxide (containing 0.5 g of graphene oxide), add 1.9 g of superconducting carbon black oxide and 1.4 g of aniline monomer, and ultrasonically disperse for 2 h to form a uniform suspension. Transfer the suspension to a reaction flask, place it in an ice-water bath at 2 °C, and slowly add 50 mL of an aqueous solution containing 2.8 g of ammonium persulfate under mechanical stirring. Continue the reaction at this low temperature for 9 h to obtain a polyaniline-grafted graphene oxide / superconducting carbon black oxide slurry. Then transfer the entire slurry to a 500 mL high-pressure reactor, add 3 mL of hydrazine hydrate, and react at 110 °C for 10 h. After the reaction, place the product in a dialysis bag and dialyze with deionized water for 3 days to remove impurities, obtaining a polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

[0027] Step 5: Pretreatment of composite conductive paste: Take 100g of polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste, adjust the pH to 4.5 with 1mol / L dilute hydrochloric acid, then add 0.4g of p-aminobenzenesulfonic acid, 0.05g of sodium nitrite and 8mL of 1mol / L dilute hydrochloric acid, stir at 2℃ for 30min to carry out diazotization reaction, then slowly raise the temperature to room temperature and continue the reaction for 3h, and then dialyze to purify again to obtain the sulfonated composite conductive paste.

[0028] Weigh 100g of aniline-pyrrole copolymer / polyurethane composite emulsion and 100g of sulfonated composite conductive paste, then add 0.3g of silicone defoamer and 0.2g of polyether-modified siloxane leveling agent. Mechanically stir at 400 rpm for 40 minutes, then let stand for 3 hours to obtain the final water-based carbon-coated aluminum foil coating.

[0029] Example 2 A method for preparing a water-based carbon-coated aluminum foil coating includes the following steps: Step 1: Add 50.0g of poly(1,4-butanediol adipate) diol (molecular weight 2000), 32g of isophorone diisocyanate, and 6g of dimethylolpropionic acid to a four-necked flask. Under nitrogen protection, react in an oil bath at 85°C for approximately 2.5 hours to obtain a polyurethane prepolymer with isocyanate end groups. Cool the system to 45°C, add 5.6g of triethylamine to neutralize the reaction for 30 minutes. Under high-speed shear at 8000 rpm, slowly pour the prepolymer into 400mL of deionized water and emulsify for 30 minutes to obtain a milky white polyurethane preemulsion.

[0030] Step 2: Add 2.0g aniline monomer, 0.6g pyrrole monomer, and 4.5g terephthalic acid sequentially to the polyurethane pre-emulsion, and stir at room temperature for 1 hour to ensure homogeneity. Then, place the reaction system in an ice-water bath at 2°C, and slowly add 50mL of an aqueous solution containing 5.5g ammonium persulfate dropwise while continuously stirring. After the addition is complete, continue the reaction at this low temperature for 10 hours to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion.

[0031] Step 3: Add 5.0 g of superconducting carbon black to a mixed acid solution consisting of 60 mL of concentrated nitric acid and 180 mL of concentrated sulfuric acid. Reflux the mixture at 70 °C and stir for 5 h. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water through vacuum filtration until the filtrate is neutral. Dry the resulting solid in a vacuum drying oven at 80 °C for 12 h to obtain oxidized superconducting carbon black.

[0032] Step 4: Take 250 mL of a 2 mg / mL aqueous dispersion of graphene oxide (containing 0.5 g of graphene oxide), add 1.6 g of superconducting carbon black oxide and 1.2 g of aniline monomer, and ultrasonically disperse for 2 h to form a uniform suspension. Transfer the suspension to a reaction flask, place it in an ice-water bath at 2 °C, and slowly add 50 mL of an aqueous solution containing 2.8 g of ammonium persulfate under mechanical stirring. Continue the reaction at this low temperature for 9 h to obtain a polyaniline-grafted graphene oxide / superconducting carbon black oxide slurry. Then transfer the entire slurry to a 500 mL high-pressure reactor, add 3 mL of hydrazine hydrate, and react at 110 °C for 10 h. After the reaction, place the product in a dialysis bag and dialyze with deionized water for 3 days to remove impurities, obtaining a polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

[0033] Step 5: Pretreatment of composite conductive paste: Take 100g of polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste, adjust the pH to 4.5 with 1mol / L dilute hydrochloric acid, then add 0.2g of p-aminobenzenesulfonic acid, 0.05g of sodium nitrite and 8mL of 1mol / L dilute hydrochloric acid, stir at 2℃ for 30min to carry out diazotization reaction, then slowly raise the temperature to room temperature and continue the reaction for 3h, and then dialyze to purify again to obtain the sulfonated composite conductive paste.

[0034] Weigh 100g of aniline-pyrrole copolymer / polyurethane composite emulsion and 100g of sulfonated composite conductive paste, then add 0.3g of silicone defoamer and 0.2g of polyether-modified siloxane leveling agent. Mechanically stir at 400 rpm for 40 minutes, then let stand for 3 hours to obtain the final water-based carbon-coated aluminum foil coating.

[0035] Example 3 A method for preparing a water-based carbon-coated aluminum foil coating includes the following steps: Step 1: Add 50.0g of poly(1,4-butanediol adipate) diol (molecular weight 2000), 35g of isophorone diisocyanate, and 7g of dimethylolpropionic acid to a four-necked flask. Under nitrogen protection, react in an oil bath at 85°C for approximately 2.5 hours to obtain a polyurethane prepolymer with isocyanate end groups. Cool the system to 45°C, add 5.6g of triethylamine to neutralize the reaction for 30 minutes. Under high-speed shear at 8000 rpm, slowly pour the prepolymer into 400mL of deionized water and emulsify for 30 minutes to obtain a milky white polyurethane preemulsion.

[0036] Step 2: Add 2.0g aniline monomer, 0.7g pyrrole monomer, and 5.0g terephthalic acid sequentially to the polyurethane pre-emulsion, and stir at room temperature for 1 hour to ensure homogeneity. Then, place the reaction system in an ice-water bath at 2°C, and slowly add 50mL of an aqueous solution containing 5.5g ammonium persulfate dropwise while continuously stirring. After the addition is complete, continue the reaction at this low temperature for 10 hours to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion.

[0037] Step 3: Add 5.0 g of superconducting carbon black to a mixed acid solution consisting of 60 mL of concentrated nitric acid and 180 mL of concentrated sulfuric acid. Reflux the mixture at 70 °C and stir for 5 h. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water through vacuum filtration until the filtrate is neutral. Dry the resulting solid in a vacuum drying oven at 80 °C for 12 h to obtain oxidized superconducting carbon black.

[0038] Step 4: Take 250 mL of a 2 mg / mL aqueous dispersion of graphene oxide (containing 0.5 g of graphene oxide), add 1.7 g of superconducting carbon black oxide and 1.3 g of aniline monomer, and ultrasonically disperse for 2 h to form a uniform suspension. Transfer the suspension to a reaction flask, place it in an ice-water bath at 2 °C, and slowly add 50 mL of an aqueous solution containing 2.8 g of ammonium persulfate under mechanical stirring. Continue the reaction at this low temperature for 9 h to obtain a polyaniline-grafted graphene oxide / superconducting carbon black oxide slurry. Then transfer the entire slurry to a 500 mL high-pressure reactor, add 3 mL of hydrazine hydrate, and react at 110 °C for 10 h. After the reaction is complete, place the product in a dialysis bag and dialyze it with deionized water for 3 days to remove impurities, obtaining a polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

[0039] Step 5: Pretreatment of composite conductive paste: Take 100g of polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste, adjust the pH to 4.5 with 1mol / L dilute hydrochloric acid, then add 0.3g of p-aminobenzenesulfonic acid, 0.05g of sodium nitrite and 8mL of 1mol / L dilute hydrochloric acid, stir at 2℃ for 30min to carry out diazotization reaction, then slowly raise the temperature to room temperature and continue the reaction for 3h, and then dialyze to purify again to obtain the sulfonated composite conductive paste.

[0040] Weigh 100g of aniline-pyrrole copolymer / polyurethane composite emulsion and 100g of sulfonated composite conductive paste, then add 0.3g of silicone defoamer and 0.2g of polyether-modified siloxane leveling agent. Mechanically stir at 400 rpm for 40 minutes, then let stand for 3 hours to obtain the final water-based carbon-coated aluminum foil coating.

[0041] Example 4 A method for preparing a water-based carbon-coated aluminum foil coating includes the following steps: Step 1: Add 50.0g of poly(1,4-butanediol adipate) diol (molecular weight 2000), 40g of isophorone diisocyanate, and 10g of dimethylolpropionic acid to a four-necked flask. Under nitrogen protection, react in an oil bath at 85°C for approximately 2.5 hours to obtain a polyurethane prepolymer with isocyanate end groups. Cool the system to 45°C, add 5.6g of triethylamine to neutralize the reaction for 30 minutes. Under high-speed shear at 8000 rpm, slowly pour the prepolymer into 400mL of deionized water and emulsify for 30 minutes to obtain a milky white polyurethane preemulsion.

[0042] Step 2: Add 2.0g aniline monomer, 1.0g pyrrole monomer, and 6.0g terephthalic acid sequentially to the polyurethane pre-emulsion, and stir at room temperature for 1 hour to ensure homogeneity. Then, place the reaction system in an ice-water bath at 2°C, and slowly add 50mL of an aqueous solution containing 5.5g ammonium persulfate dropwise while continuously stirring. After the addition is complete, continue the reaction at this low temperature for 10 hours to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion.

[0043] Step 3: Add 5.0 g of superconducting carbon black to a mixed acid solution consisting of 60 mL of concentrated nitric acid and 180 mL of concentrated sulfuric acid. Reflux the mixture at 70 °C and stir for 5 h. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water through vacuum filtration until the filtrate is neutral. Dry the resulting solid in a vacuum drying oven at 80 °C for 12 h to obtain oxidized superconducting carbon black.

[0044] Step 4: Take 250 mL of a 2 mg / mL aqueous dispersion of graphene oxide (containing 0.5 g of graphene oxide), add 2.0 g of superconducting carbon black oxide and 1.5 g of aniline monomer, and ultrasonically disperse for 2 h to form a uniform suspension. Transfer the suspension to a reaction flask, place it in a 5℃ ice-water bath, and slowly add 50 mL of an aqueous solution containing 2.8 g of ammonium persulfate under mechanical stirring. Continue the reaction at this low temperature for 10 h to obtain a polyaniline-grafted graphene oxide / superconducting carbon black oxide slurry. Then transfer the entire slurry to a 500 mL high-pressure reactor, add 3 mL of hydrazine hydrate, and react at 110℃ for 10 h. After the reaction, place the product in a dialysis bag and dialyze with deionized water for 3 days to remove impurities, obtaining a polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

[0045] Step 5: Pretreatment of composite conductive paste: Take 100g of polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste, adjust the pH to 5 with 1mol / L dilute hydrochloric acid, then add 0.5g of p-aminobenzenesulfonic acid, 0.05g of sodium nitrite and 8mL of 1mol / L dilute hydrochloric acid, stir at 2℃ for 30min to carry out diazotization reaction, then slowly raise the temperature to room temperature and continue the reaction for 3h, and then dialyze to purify again to obtain the sulfonated composite conductive paste.

[0046] Weigh 100g of aniline-pyrrole copolymer / polyurethane composite emulsion and 100g of sulfonated composite conductive paste, then add 0.3g of silicone defoamer and 0.2g of polyether-modified siloxane leveling agent. Mechanically stir at 400 rpm for 40 minutes, then let stand for 3 hours to obtain the final water-based carbon-coated aluminum foil coating.

[0047] Example 5 A method for preparing a water-based carbon-coated aluminum foil coating includes the following steps: Step 1: Add 50.0g of poly(1,4-butanediol adipate) diol (molecular weight 2000), 30g of isophorone diisocyanate, and 5.0g of dimethylolpropionic acid to a four-necked flask. Under nitrogen protection, react in an oil bath at 85°C for approximately 2.5 hours to obtain a polyurethane prepolymer with isocyanate end groups. Cool the system to 45°C, add 5.6g of triethylamine to neutralize the reaction for 30 minutes. Under high-speed shear at 8000 rpm, slowly pour the prepolymer into 400mL of deionized water and emulsify for 30 minutes to obtain a milky white polyurethane preemulsion.

[0048] Step 2: Add 2.0g aniline monomer, 0.5g pyrrole monomer, and 4.0g terephthalic acid sequentially to the polyurethane pre-emulsion, and stir at room temperature for 1 hour to ensure homogeneity. Then, place the reaction system in an ice-water bath at 2°C, and slowly add 50mL of an aqueous solution containing 5.5g ammonium persulfate dropwise while continuously stirring. After the addition is complete, continue the reaction at this low temperature for 10 hours to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion.

[0049] Step 3: Add 5.0 g of superconducting carbon black to a mixed acid solution consisting of 60 mL of concentrated nitric acid and 180 mL of concentrated sulfuric acid. Reflux the mixture at 70 °C and stir for 5 h. After the reaction is complete, cool to room temperature and wash repeatedly with deionized water through vacuum filtration until the filtrate is neutral. Dry the resulting solid in a vacuum drying oven at 80 °C for 12 h to obtain oxidized superconducting carbon black.

[0050] Step 4: Take 250 mL of a 2 mg / mL aqueous dispersion of graphene oxide (containing 0.5 g of graphene oxide), add 1.5 g of superconducting carbon black oxide and 1.0 g of aniline monomer, and ultrasonically disperse for 2 h to form a uniform suspension. Transfer the suspension to a reaction flask, place it in a 0℃ ice-water bath, and slowly add 50 mL of an aqueous solution containing 2.8 g of ammonium persulfate under mechanical stirring. Continue the reaction at this low temperature for 8 h to obtain a polyaniline-grafted graphene oxide / superconducting carbon black oxide slurry. Then transfer the entire slurry to a 500 mL high-pressure reactor, add 3 mL of hydrazine hydrate, and react at 110℃ for 10 h. After the reaction, place the product in a dialysis bag and dialyze with deionized water for 3 days to remove impurities, obtaining a polyaniline-grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

[0051] Step 5: Pretreatment of composite conductive paste: Take 100g of polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive paste, adjust the pH to 4 with 1mol / L dilute hydrochloric acid, then add 0.1g of p-aminobenzenesulfonic acid, 0.05g of sodium nitrite and 8mL of 1mol / L dilute hydrochloric acid, stir at 2℃ for 30min to carry out diazotization reaction, then slowly raise the temperature to room temperature and continue the reaction for 3h, and then dialyze to purify again to obtain the sulfonated composite conductive paste.

[0052] Weigh 100g of aniline-pyrrole copolymer / polyurethane composite emulsion and 100g of sulfonated composite conductive paste, then add 0.3g of silicone defoamer and 0.2g of polyether-modified siloxane leveling agent. Mechanically stir at 400 rpm for 40 minutes, then let stand for 3 hours to obtain the final water-based carbon-coated aluminum foil coating.

[0053] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step 2 is omitted in the preparation process of the water-based carbon-coated aluminum foil coating.

[0054] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 4 is omitted in the preparation process of the water-based carbon-coated aluminum foil coating, and the sulfonated composite conductive slurry in step 5 is replaced with superconducting carbon black oxide.

[0055] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the composite conductive paste in step 5 of the preparation process of the water-based carbon-coated aluminum foil coating did not undergo sulfonation pretreatment.

[0056] Performance testing: 1. Coating Surface Resistivity Test: Following GB / T 1410-2006 "Test Methods for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", a four-probe resistance tester was used for testing. First, the coating was applied to a 10μm thick pure aluminum foil surface using a microgravure coating machine (coating speed 3m / min), and dried in an 80℃ forced-air drying oven for 30min, controlling the dry film thickness to be 2±0.3μm. Then, five evenly distributed test points were selected on the coating surface (avoiding the 1cm edge area), a 10V test voltage was applied, and the surface resistance value at each point was recorded. The final result was the average of the five points, expressed in Ω / □. The test results are shown in Table 1.

[0057] 2. Volume resistivity test: The coating was applied to a polytetrafluoroethylene mold (size: 50mm×50mm×2mm), and dried at 80℃ for 2 hours to prepare a standard sample. A high-resistivity meter was used with a three-electrode system (protective electrode, measuring electrode, and high-voltage electrode). A voltage of 100V was applied at 25℃ and 50% RH. After the reading stabilized, the volume resistivity was recorded in Ω•cm. The average value of three parallel samples was taken. The test results are shown in Table 1.

[0058] 3. Coating Adhesion Test: Following GB / T 9286-1998 "Paints and Varnishes - Cross-cut Test", a cross-cutting tool (1mm spacing, 6 blades) was used to cut a grid across the coated aluminum foil surface (penetrating to the aluminum foil substrate). Debris in the cut areas was removed with a soft brush. Then, 3M 600 tape was applied and quickly peeled off at a 45° angle. The extent of coating peeling at the intersections of the cuts was observed and graded according to the standard (Grade 0: no peeling; Grade 1: slight peeling at the intersection; Grade 2: significant peeling at the intersection; Grade 3: peeling along the edge of the scratch; Grade 4: large-area peeling). The highest grade was recorded for three different areas tested. The test results are shown in Table 1.

[0059] 4. Electrolyte stability test: Simulating the electrolyte environment of a lithium battery, a 1 mol / L LiPF6 / EC+DMC (volume ratio 1:1) electrolyte was prepared. Coated aluminum foil was cut into 20 mm × 20 mm samples, immersed in the electrolyte, and left to stand in an 85℃ constant temperature oven for 24 hours. After removing the samples, the surface was wiped with anhydrous ethanol, dried, and the surface resistance was measured. The surface resistance change rate (%) was calculated as: (resistance after immersion - resistance before immersion) / resistance before immersion × 100%. The average value of three parallel samples was taken. The test results are shown in Table 1.

[0060] Table 1: Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing an aqueous carbon-coated aluminum foil coating material, characterized by, The method comprises the following steps: S1, reacting polybutylene adipate glycol, isophorone diisocyanate and dimethylol propionic acid to obtain a polyurethane prepolymer with isocyanate groups at the end, then adding triethylamine for neutralization, and emulsifying in the presence of water to obtain a polyurethane pre-emulsion; S2, adding aniline monomer, pyrrole monomer, p-benzenedisulfonic acid and ammonium persulfate into the polyurethane pre-emulsion for polymerization to obtain an aniline-pyrrole copolymer / polyurethane composite emulsion; S3, treating superconducting carbon black with a mixed acid of concentrated nitric acid and concentrated sulfuric acid to obtain oxidized superconducting carbon black; S4, mixing graphene oxide, oxidized superconducting carbon black and aniline monomer, then adding ammonium persulfate for polymerization to obtain a polyaniline grafted graphene oxide / oxidized superconducting carbon black slurry, and performing a hydrothermal reduction reaction of the slurry with hydrazine hydrate to obtain a polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry; S5, taking the polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry, adjusting the pH to 4-5, then adding p-aminobenzenesulfonic acid, sodium nitrite and dilute hydrochloric acid for reaction to obtain a pretreated polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry; Mixing the aniline-pyrrole copolymer / polyurethane composite emulsion, the pretreated polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry, a silicone defoaming agent and a polyether modified siloxane leveling agent, stirring and then standing for curing to obtain a water-based carbon-coated aluminum foil paint.

2. The method for preparing a water-based carbon-coated aluminum foil coating according to claim 1, characterized in that, In step S1, the mass ratio of polybutylene adipate glycol to isophorone diisocyanate is 5:3-4.

3. The method of claim 1, wherein the aqueous carbon black coating for aluminum foil is prepared by adding 0.1 to 0.5 parts by weight of a dispersant to 100 parts by weight of a carbon black, and then adding 0.1 to 0.5 parts by weight of a thickener to the mixture. In step S1, the addition amount of dimethylol propionic acid is 10-20wt% of the mass of polybutylene adipate glycol.

4. The method of claim 1, wherein the aqueous carbon black coating for aluminum foil is prepared by adding 0.1 to 0.5 parts by weight of a dispersant to 100 parts by weight of a carbon black, and then adding 0.1 to 0.5 parts by weight of a thickener to the mixture. In step S2, the mass ratio of aniline monomer to pyrrole monomer is 2:0.5-1.

0.

5. The method of claim 1, wherein the aqueous carbon black coating for aluminum foil is prepared by adding 0.1 to 0.5 parts by weight of a dispersant to 100 parts by weight of a carbon black, and then adding 0.1 to 0.5 parts by weight of a thickener to the mixture. In step S2, the mass ratio of aniline monomer to p-benzenedisulfonic acid is 1:2-3.

6. The method for preparing a water-based carbon-coated aluminum foil coating according to claim 1, characterized in that, In step S4, the mass ratio of graphene oxide, oxidized superconducting carbon black and aniline monomer is 1:3-4:2-3.

7. The method for preparing a water-based carbon-coated aluminum foil coating according to claim 1, characterized in that, In step S4, the polymerization temperature is 0-5℃, and the polymerization time is 8-10h.

8. The method for preparing a water-based carbon-coated aluminum foil coating according to claim 1, characterized in that, In step S5, the addition amount of p-aminobenzenesulfonic acid is 0.1-0.5wt% of the mass of the polyaniline grafted reduced graphene oxide / superconducting carbon black composite conductive slurry.

9. An aqueous carbon-coated aluminum foil coating material, characterized by, Prepared by the method of any one of claims 1-8.

Images