A method for the preparation of a corrosion-resistant, electrically conductive composite coating for electrodes

Abstract

This invention discloses a method for preparing a corrosion-resistant and conductive composite coating for electrodes in the field of electrochemical technology. The method first pre-treats the surface of a copper electrode by grinding and cleaning. Then, a specially prepared yttrium-functionalized two-dimensional layered carbonitride and Schiff base two-dimensional heterostructure material are dispersed in a mixed solvent and formulated with epoxy resin, additives, and a curing agent to form a coating slurry. This slurry is then sprayed and cured in stages onto the electrode surface to form a composite coating. The key modifying material used in this coating is obtained by interfacial assembly of titanium aluminum carbide (after fluorosulfonic acid exfoliation and amination) with a Schiff base complex synthesized from dihydroxyterephthalaldehyde and diaminocyclohexane and coordinated with yttrium ions, followed by heat treatment. This material forms a stable heterostructure in the coating, synergistically exhibiting excellent conductivity and corrosion resistance. The resulting coating has advantages such as strong adhesion, low resistivity, and good salt spray resistance. The preparation process is simple and suitable for the protection of various industrial electrodes.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically to a method for preparing a corrosion-resistant conductive composite coating for electrodes. Background Technology

[0002] Metal electrodes play an irreplaceable role in many fields, including electrochemical industry, energy conversion and storage, and marine engineering. However, these electrodes are exposed to corrosive media such as acids, alkalis, and salts for extended periods, making their surfaces susceptible to electrochemical corrosion. This leads to a reduction in active area, decreased conductivity, and shortened lifespan, ultimately affecting the overall system's operating efficiency and stability. Traditional electrode protection strategies primarily rely on noble metal plating, carbon-based material coatings, or polymer coatings. While noble metal plating combines excellent conductivity and chemical inertness, its high cost limits large-scale industrial applications. Carbon-based coatings, such as graphene, offer excellent conductivity, but they can form galvanic corrosion cells upon contact with the metal substrate, accelerating localized corrosion of the substrate. Polymer coatings generally suffer from inherently poor conductivity, making it difficult to meet the current conduction requirements of the electrode during operation. These traditional materials all have significant limitations, failing to provide durable and reliable corrosion protection while ensuring high conductivity.

[0003] To overcome the shortcomings of single materials, existing technologies attempt to develop composite coating systems. For example, some studies have used the method of introducing metallic phases into ceramic matrices to construct interpenetrating networks, aiming to synergistically improve corrosion resistance and conductivity. However, these methods often rely on complex and expensive processes such as high-temperature pyrolysis and 3D printing, requiring sophisticated equipment and hindering widespread adoption. Another mainstream research direction is the introduction of two-dimensional nanomaterials as functional fillers, but simple physical blending can easily lead to uneven dispersion and stacking of fillers in the resin matrix, resulting in unstable coating performance. A more fundamental scientific challenge lies in the inherent contradiction between conductivity and corrosion resistance: highly conductive materials typically achieve conductivity through free electron transport, which provides a pathway for electrochemical corrosion in corrosive media; while high-performance anti-corrosion coatings tend to construct robust physical barriers to inhibit ion and electron migration, which contradicts the requirement for conductivity. Therefore, developing a novel coating material and a simple preparation method that can fundamentally synergistically optimize these two properties has become a critical technological bottleneck that urgently needs to be overcome in this field.

[0004] To address the aforementioned challenges, this invention aims to propose a novel solution. Its core lies in designing and synthesizing a modified material with a unique two-dimensional heterostructure. This material, through ingenious molecular design, combines the conductivity advantages of inorganic two-dimensional materials with the passivation capabilities of organometallic complexes. This allows for the construction of a highly efficient conductive network within the coating while providing a labyrinthine physical barrier and active electrochemical protection. This strategy aims to resolve the contradiction between conductivity and corrosion resistance at the material's fundamental level. Coupled with an extremely simplified coating preparation process, a dense, stable, and functionally integrated composite coating can be formed on the electrode surface simply through spraying and curing, providing a new technical approach for the long-term, stable operation of high-performance electrodes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a corrosion-resistant and conductive composite coating for electrodes, which solves the technical problems that existing electrode coatings cannot simultaneously achieve high conductivity and long-term corrosion resistance, and that the preparation process is complex and costly.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A method for preparing a corrosion-resistant conductive composite coating for electrodes includes the following steps:

[0008] S1. Polish the copper surface with sandpaper until the surface roughness Ra is 0.8-1.2μm; then ultrasonically clean the copper in acetone, ethanol and deionized water in sequence; dry the cleaned copper in an oven and cool it to room temperature to obtain the pretreated copper surface.

[0009] S2, Yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material is dispersed in a mixed solvent composed of xylene and n-butanol, and ultrasonically treated; epoxy resin, leveling agent and defoamer are added, and stirred to obtain a slurry; polyamide is added under stirring, and stirring is continued to obtain a coating slurry;

[0010] S3, spray the coating paste onto the pretreated copper surface; after spraying, allow it to dry at room temperature.

[0011] S4, then put it into a forced-air oven for step curing: first cure at 78-82℃, then heat up to 145-155℃ for curing, and after curing, cool it to room temperature with the oven.

[0012] In this invention, the reaction mechanism for preparing the corrosion-resistant conductive composite coating for electrodes is mainly based on the synergistic effect of epoxy resin curing and crosslinking and the construction of a functional filler network. The process begins with a copper electrode substrate that has undergone rigorous surface treatment; its specific roughness and clean surface provide excellent mechanical anchoring points and chemical bonding interfaces for the coating. During the coating slurry preparation stage, yttrium-functionalized two-dimensional layered carbonitrides and Schiff base two-dimensional heterostructure materials are dispersed at the nanoscale in a mixed solvent through ultrasonic treatment. The organic components on their surface have good compatibility with the epoxy resin, preventing filler agglomeration and sedimentation. When the polyamide curing agent is added, its terminal amino groups undergo ring-opening polymerization with the epoxy groups on the epoxy resin molecular chains. This is a gradually increasing curing and crosslinking process, ultimately forming a three-dimensional network-like polymer framework. In this polymer curing network, the two-dimensional heterostructure material, acting as a functional filler, utilizes its large specific surface area and layered structure to construct a crisscrossing physical barrier network in the coating, greatly extending the penetration path of corrosive media such as water molecules and chloride ions. More importantly, the filler itself constitutes a highly efficient electron conduction channel. The yttrium-Schiff base complex units on its surface promote electron tunneling through intramolecular electron delocalization, thus endowing the coating with excellent bulk conductivity. The stepped curing process ensures the full and thorough cross-linking reaction of the epoxy resin and promotes the interaction between the polymer chain segments and the filler interface, reducing internal stress. The final composite coating is a dense organic-inorganic hybrid protective layer. The continuous epoxy resin phase provides basic adhesion and chemical stability, while the uniformly dispersed two-dimensional heterostructure filler phase synergistically contributes excellent conductivity and a labyrinthine corrosion barrier. Furthermore, yttrium ions can migrate to the metal interface to form a passivation film when the coating is locally damaged, exhibiting intelligent self-healing properties. This achieves long-term and reliable corrosion protection and improved electrical performance of the electrode material.

[0013] According to a preferred embodiment of the present invention, in step S1, the drying temperature in the oven is 45-55°C.

[0014] According to a preferred embodiment of the present invention, in step S2, the ultrasonic treatment time is 30-40 min.

[0015] According to a preferred embodiment of the present invention, in step S3, the surface drying time at room temperature is 15-20 minutes.

[0016] According to a preferred embodiment of the present invention, in step S4, the curing time is 1-2 hours at 78-82°C; and the curing time is 2-4 hours when the temperature is raised to 145-155°C.

[0017] According to a preferred embodiment of the present invention, the preparation steps of the yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material include:

[0018] A1. Titanium aluminum carbide was placed in a reaction vessel, and an aqueous solution of fluorosulfonic acid was added. The mixture was stirred and reacted at 34-36℃. After the reaction was completed, the precipitate was collected by centrifugation and washing. The precipitate was redispersed in N,N-dimethylformamide to obtain a dispersion. 3-aminopropyltriethoxysilane was added to the dispersion, and the mixture was refluxed at 58-62℃, centrifuged, and vacuum dried to obtain an aminated two-dimensional layered carbonitride.

[0019] A2, 2,5-Dihydroxyterephthalaldehyde and 1,2-diaminocyclohexane were dissolved in anhydrous ethanol to obtain aldehyde and amine solutions, respectively. Under nitrogen protection, the amine solution was added dropwise to the aldehyde solution. After the addition was complete, the temperature was raised to 68-72℃ to react and obtain a Schiff base ligand. The Schiff base ligand was mixed with yttrium nitrate hexahydrate in an acetonitrile / ethanol mixed solvent, and triethylamine was added. The mixture was stirred at 78-82℃. After the reaction was completed, the mixture was rotary evaporated, washed with diethyl ether, and dried under vacuum to obtain the yttrium-Schiff base complex.

[0020] A3. The aminated two-dimensional layered carbonitride was redispersed in a mixed solvent of anhydrous ethanol and N,N-dimethylformamide and sonicated to obtain a dispersion. The yttrium-Schiff base complex was dissolved in a mixed solvent of anhydrous ethanol and N,N-dimethylformamide and added dropwise to the dispersion with stirring. Sodium cyanoborohydride was added. After the addition was complete, stirring was continued. After the reaction was completed, the solid product was collected by centrifugation and washed alternately with ethanol and deionized water to obtain the washed solid product.

[0021] A4. The washed solid product is heat-treated under a nitrogen atmosphere: the temperature is raised to 195-205℃ and held; the temperature is raised to 345-355℃ and held; the product is obtained, and the product is ground into powder and sieved.

[0022] In this invention, the preparation mechanism of yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure materials involves a multi-step process of fine chemical synthesis and interfacial assembly. This process begins with the selective etching and simultaneous functionalization of the two-dimensional layered carbonitride precursor in a fluorosulfonic acid solution. The fluorosulfonic acid not only effectively removes the aluminum atomic layers between the layers, achieving the exfoliation of the two-dimensional structure, but also introduces active sites such as sulfonic acid groups onto its surface, laying the foundation for subsequent reactions. Subsequently, through the condensation reaction of a silane coupling agent with surface functional groups, amino groups are successfully grafted onto the surface of the two-dimensional layered carbonitride, obtaining an aminated intermediate. Simultaneously, dihydroxyterephthalaldehyde and diaminocyclohexane undergo a Schiff base condensation reaction to generate an organic ligand containing bidentate coordination sites. This ligand then undergoes a coordination reaction with yttrium ions to form a structurally stable yttrium-Schiff base complex. The most crucial step lies in the interfacial self-assembly between the aminated two-dimensional layered carbonitride and the yttrium-Schiff base complex. The amino group undergoes a secondary Schiff base reaction with the residual aldehyde group in the complex, and under the reducing stabilization effect of sodium cyanoborohydride, a strong carbon-nitrogen single bond is formed, rather than a reversible imine bond, thus constructing a stable heterostructure with a two-dimensional material as the framework and organometallic complexes as the functional units. The final heat treatment process promotes intermolecular cross-linking and increases crystallinity within the heterostructure, further enhancing its structural stability and optimizing the electronic band structure, ultimately yielding a functional material with both high conductivity and surface activity.

[0023] According to a preferred embodiment of the present invention, in step A1, the reflux time at 58-62°C is 6-8 hours.

[0024] According to a preferred embodiment of the present invention, in step A2, the stirring reaction time is 8-10 h at 78-82°C.

[0025] According to a preferred embodiment of the present invention, in step A3, the stirring time is continued for 24-30 hours.

[0026] According to a preferred embodiment of the present invention, in step A4, the temperature is raised to 195-205°C and held for 2-4 hours.

[0027] The beneficial effects of this invention are as follows:

[0028] The corrosion-resistant and conductive composite coating preparation method for electrodes provided by this invention achieves multiple breakthroughs in technical performance by introducing a unique yttrium-functionalized two-dimensional layered carbonitride and Schiff base two-dimensional heterostructure material. This modified material, through precise molecular design and interface engineering, successfully constructs a stable two-dimensional heterostructure. The two-dimensional layered carbonitride provides efficient electron transport channels, while the yttrium-Schiff base complex, through its unique electronic structure and coordination properties, forms an electron tunneling effect at the material interface, significantly improving conductivity. Simultaneously, this heterostructure forms a labyrinthine physical barrier within the coating, effectively blocking the penetration of corrosive media. More importantly, the introduction of yttrium ions endows the coating with self-healing passivation capabilities. When the coating is locally damaged, yttrium ions can migrate to the damaged area to form a dense passivation film, preventing further corrosion. This synergistic effect fundamentally solves the technical problem of the mutual constraint between conductivity and corrosion resistance in traditional coatings.

[0029] From a manufacturing process perspective, this invention represents a significant technological advancement. The coating preparation process comprises only four simple steps: surface treatment, slurry preparation, spray application, and stepped curing. All raw materials are commercially available industrial products, enabling large-scale production without complex equipment. This simplified process not only significantly reduces production costs and equipment investment but also ensures the consistency and stability of coating quality. Of particular note is the precisely controlled stepped curing process, which enables a robust interfacial bond between the epoxy resin crosslinking network and the functional heterogeneous structure material. This ensures both the density and adhesion of the coating and the uniform distribution of the functional fillers, avoiding problems such as filler agglomeration and sedimentation common in traditional processes, thereby optimizing coating performance.

[0030] In summary, the composite coating prepared by this invention exhibits superior overall performance. Regarding conductivity, the surface resistivity of the coating is significantly reduced, and the charge transfer efficiency is greatly improved, fully meeting the conductivity requirements of electrode operation. In terms of corrosion resistance, the coating demonstrates protection capabilities far exceeding those of traditional coatings in salt spray tests and electrochemical impedance spectroscopy, with its impedance modulus several orders of magnitude higher than that of conventional graphene-reinforced coatings, and it also exhibits excellent long-term stability. Furthermore, the coating displays good adhesion, impact resistance, and thermal stability, enabling it to adapt to various harsh industrial environments. This combination of high conductivity, durable corrosion protection, and robustness makes this invention particularly suitable for electrode protection in fields such as electrolysis, marine engineering, and new energy batteries, effectively extending electrode lifespan, improving system operating efficiency and reliability, and possessing broad industrial application prospects. Detailed Implementation

[0031] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0032] The following is information on domestic suppliers of the relevant equipment and materials:

[0033] The epoxy resin was purchased from Jinan Chuangshi Chemical Co., Ltd.

[0034] The leveling agent was purchased from Nantong Runfeng Petrochemical Co., Ltd.

[0035] The defoamer was purchased from Shandong Tuoxing Chemical Technology Co., Ltd.

[0036] The titanium aluminum carbide was purchased from MAX phase by Forsmann Technology (Beijing) Co., Ltd.

[0037] The 2,5-dihydroxyterephthalaldehyde was purchased from Zhengzhou Alpha Chemical Co., Ltd.

[0038] The 1,2-diaminocyclohexane was purchased from Shanghai Bangcheng Chemical Co., Ltd.

[0039] Example 1: Preparation of Yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material: First, 2.0 g of titanium aluminum carbide powder was placed in a 250 mL polytetrafluoroethylene reactor, and 100 g of 40% (w / w) fluorosulfonic acid aqueous solution was added. The mixture was magnetically stirred at 300 rpm for 24 h at 35 °C. After the reaction, the mixture was centrifuged at 8000 rpm for 10 min, the supernatant was discarded, and the mixture was repeatedly washed with deionized water until the pH of the supernatant reached 6.5. The precipitate was collected and redispersed in 200 mL of N,N-dimethylformamide to obtain a dispersion with a concentration of 5 mg / mL. 5 mL of 3-aminopropyltriethoxysilane was added to the dispersion, and the mixture was refluxed at 60 °C for 7 h. Then, the solid was collected by centrifugation at 10000 rpm for 15 min and dried in a vacuum drying oven at 60 °C for 12 h to obtain aminated two-dimensional layered carbonitride. Simultaneously, 5.0 g of 2,5-dihydroxyterephthalaldehyde and 3.8 g of 1,2-diaminocyclohexane were dissolved in 100 mL of anhydrous ethanol. Under nitrogen protection, the amine solution was slowly added dropwise to the aldehyde solution at a rate of 2 mL / min using a constant pressure dropping funnel. After the addition was complete, the temperature was raised to 70 °C and the reaction was carried out for 12 h to obtain a yellow Schiff base ligand solution. 2.0 g of this Schiff base ligand was mixed with 1.2 g of yttrium nitrate hexahydrate in 100 mL of a 1:1 volume ratio acetonitrile-ethanol mixture. 0.5 mL of triethylamine was added, and the mixture was stirred at 80 °C and 400 rpm for 9 h. After the reaction was completed, the solvent was removed by rotary evaporation at 50 °C. The mixture was washed three times with 100 mL of diethyl ether and dried in a vacuum drying oven at 50 °C for 8 h to obtain a pale yellow yttrium-Schiff base complex. 1.0 g of the aminated two-dimensional layered carbonitride was redispersed in a mixed solvent of 150 mL anhydrous ethanol and 150 mL N,N-dimethylformamide, and sonicated at 600 W for 2 h. 1.5 g of the yttrium-Schiff base complex was dissolved in 150 mL of the same mixed solvent and added dropwise to the dispersion at a rate of 3 mL / min while stirring at 800 rpm. Simultaneously, 0.1 g of sodium cyanoborohydride was added, and stirring continued at 500 rpm for 26 h after the addition was complete. After the reaction was complete, the solid product was collected by centrifugation at 10000 rpm for 20 min and washed three times alternately with 100 mL ethanol and 100 mL deionized water to obtain the washed solid product. The solid product was placed in a tube furnace and heated to 200°C at a heating rate of 2°C / min under a nitrogen atmosphere and held for 3 hours. Then, it was heated to 350°C at a heating rate of 1°C / min and held for 4 hours. The resulting product was ground into powder in a mortar and passed through a 400-mesh sieve to obtain the final modified material.

[0040] Preparation of a corrosion-resistant conductive composite coating for electrodes: A copper plate with dimensions of 50mm × 50mm × 1mm was used as the substrate and polished with 800-grit sandpaper until the surface roughness Ra was 1.0μm. The copper plate was then sequentially immersed in 100mL acetone, 100mL ethanol, and 100mL deionized water for ultrasonic cleaning for 15min each. After cleaning, the copper plate was dried in a 50℃ oven for 2h and cooled to room temperature to obtain a pretreated surface. 8.0g of the modified material prepared above was dispersed in a mixed solvent consisting of 35g xylene and 15g n-butanol and ultrasonically treated at 400W for 35min. 100g epoxy resin, 0.5g leveling agent, and 0.3g defoamer were added, and the mixture was mechanically stirred at 1200rpm for 1h to obtain a uniform slurry. 35g polyamide curing agent was added under low-speed stirring at 300rpm, and stirring was continued for 15min to obtain the coating slurry. The coating slurry was uniformly sprayed onto the pretreated copper surface using a spray gun under a pressure of 0.3 MPa, with the wet film thickness controlled at 180 μm. After spraying, the coating was surface-dried at room temperature (25°C) for 18 min, and then placed in a forced-air oven for stepped curing: first cured at 80°C for 1.5 h, then the temperature was increased to 150°C at a rate of 2°C / min for 3 h. After curing, the coating was cooled to room temperature in the oven to obtain the final composite coating.

[0041] Example 2: Preparation of Yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material: First, 1.5 g of titanium aluminum carbide powder was placed in a 250 mL polytetrafluoroethylene reactor, and 75 g of 40% (w / w) fluorosulfonic acid aqueous solution was added. The mixture was magnetically stirred at 300 rpm for 26 h at 34 °C. After the reaction, the mixture was centrifuged at 8000 rpm for 10 min, the supernatant was discarded, and the mixture was repeatedly washed with deionized water until the pH of the supernatant reached 6.5. The precipitate was collected and redispersed in 150 mL of N,N-dimethylformamide to obtain a dispersion with a concentration of 5 mg / mL. 4 mL of 3-aminopropyltriethoxysilane was added to the dispersion, and the mixture was refluxed at 58 °C for 8 h. Then, the solid was collected by centrifugation at 10000 rpm for 15 min and dried in a vacuum drying oven at 60 °C for 12 h to obtain aminated two-dimensional layered carbonitride. Simultaneously, 4.0 g of 2,5-dihydroxyterephthalaldehyde and 3.0 g of 1,2-diaminocyclohexane were dissolved in 80 mL of anhydrous ethanol. Under nitrogen protection, the amine solution was slowly added dropwise to the aldehyde solution at a rate of 2 mL / min using a constant pressure dropping funnel. After the addition was complete, the temperature was raised to 68 °C and the reaction was carried out for 13 h to obtain a yellow Schiff base ligand solution. 1.5 g of this Schiff base ligand was mixed with 0.9 g of yttrium nitrate hexahydrate in 80 mL of a 1:1 volume ratio acetonitrile-ethanol mixture. 0.4 mL of triethylamine was added, and the mixture was stirred at 78 °C and 400 rpm for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation at 50 °C. The mixture was washed three times with 80 mL of diethyl ether and dried in a vacuum drying oven at 50 °C for 8 h to obtain a pale yellow yttrium-Schiff base complex. 0.8 g of the aminated two-dimensional layered carbonitride was redispersed in a mixed solvent of 120 mL anhydrous ethanol and 120 mL N,N-dimethylformamide, and sonicated at 600 W for 2 h. 1.2 g of the yttrium-Schiff base complex was dissolved in 120 mL of the same mixed solvent and added dropwise to the dispersion at a rate of 3 mL / min while stirring at 800 rpm. Simultaneously, 0.08 g of sodium cyanoborohydride was added, and stirring continued at 500 rpm for 28 h after the addition was complete. After the reaction was complete, the solid product was collected by centrifugation at 10000 rpm for 20 min and washed three times alternately with 80 mL of ethanol and 80 mL of deionized water to obtain the washed solid product. The solid product was placed in a tube furnace and heated to 195°C at a heating rate of 2°C / min under a nitrogen atmosphere and held for 4 hours. Then, it was heated to 345°C at a heating rate of 1°C / min and held for 5 hours. The resulting product was ground into powder in a mortar and passed through a 400-mesh sieve to obtain the final modified material.

[0042] Preparation of a corrosion-resistant conductive composite coating for electrodes: A copper plate with dimensions of 50mm × 50mm × 1mm was used as the substrate and polished with 800-grit sandpaper until the surface roughness Ra was 1.0μm. The copper plate was then sequentially immersed in 100mL acetone, 100mL ethanol, and 100mL deionized water for ultrasonic cleaning for 15min each. After cleaning, the copper plate was dried in a 45℃ oven for 2.5h and cooled to room temperature to obtain a pretreated surface. 12g of the modified material prepared above was dispersed in a mixed solvent consisting of 40g xylene and 10g n-butanol and ultrasonically treated at 400W for 30min. 100g epoxy resin, 0.5g leveling agent, and 0.3g defoamer were added, and the mixture was mechanically stirred at 1200rpm for 1h to obtain a uniform slurry. 30g polyamide curing agent was added under low-speed stirring at 300rpm, and stirring was continued for 15min to obtain the coating slurry. The coating slurry was uniformly sprayed onto the pretreated copper surface using a spray gun under a pressure of 0.3 MPa, with the wet film thickness controlled at 180 μm. After spraying, the coating was surface-dried at room temperature (25°C) for 15 min, and then placed in a forced-air oven for stepped curing: first cured at 78°C for 2 h, then the temperature was increased to 145°C at a rate of 2°C / min for 4 h. After curing, the coating was cooled to room temperature in the oven to obtain the final composite coating.

[0043] Example 3: Preparation of Yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material: First, 2.2 g of titanium aluminum carbide powder was placed in a 250 mL polytetrafluoroethylene reactor, and 110 g of 40% (w / w) fluorosulfonic acid aqueous solution was added. The mixture was magnetically stirred at 300 rpm for 22 h at 36 °C. After the reaction, the mixture was centrifuged at 8000 rpm for 10 min, the supernatant was discarded, and the mixture was repeatedly washed with deionized water until the pH of the supernatant reached 6.5. The precipitate was collected and redispersed in 220 mL of N,N-dimethylformamide to obtain a dispersion with a concentration of 5 mg / mL. 6 mL of 3-aminopropyltriethoxysilane was added to the dispersion, and the mixture was refluxed at 62 °C for 6 h. Then, the solid was collected by centrifugation at 10000 rpm for 15 min and dried in a vacuum drying oven at 60 °C for 12 h to obtain aminated two-dimensional layered carbonitride. Simultaneously, 6.0 g of 2,5-dihydroxyterephthalaldehyde and 4.6 g of 1,2-diaminocyclohexane were dissolved in 120 mL of anhydrous ethanol. Under nitrogen protection, the amine solution was slowly added dropwise to the aldehyde solution at a rate of 2 mL / min using a constant pressure dropping funnel. After the addition was complete, the temperature was raised to 72 °C and the reaction was carried out for 11 h to obtain a yellow Schiff base ligand solution. 2.5 g of this Schiff base ligand was mixed with 1.5 g of yttrium nitrate hexahydrate in 120 mL of a 1:1 volume ratio acetonitrile-ethanol mixture. 0.6 mL of triethylamine was added, and the mixture was stirred at 82 °C and 400 rpm for 8 h. After the reaction was completed, the solvent was removed by rotary evaporation at 50 °C. The mixture was washed three times with 120 mL of diethyl ether and dried in a vacuum drying oven at 50 °C for 8 h to obtain a pale yellow yttrium-Schiff base complex. 1.2 g of the aminated two-dimensional layered carbonitride was redispersed in a mixed solvent of 180 mL anhydrous ethanol and 180 mL N,N-dimethylformamide, and sonicated at 600 W for 2 h. 1.8 g of the yttrium-Schiff base complex was dissolved in 180 mL of the same mixed solvent and added dropwise to the dispersion at a rate of 3 mL / min while stirring at 800 rpm. Simultaneously, 0.12 g of sodium cyanoborohydride was added, and stirring continued at 500 rpm for 24 h after the addition was complete. After the reaction was complete, the solid product was collected by centrifugation at 10000 rpm for 20 min and washed three times alternately with 120 mL ethanol and 120 mL deionized water to obtain the washed solid product. The solid product was placed in a tube furnace and heated to 205°C at a heating rate of 2°C / min under a nitrogen atmosphere and held for 2 hours. Then, it was heated to 355°C at a heating rate of 1°C / min and held for 3 hours. The resulting product was ground into powder in a mortar and passed through a 400-mesh sieve to obtain the final modified material.

[0044] Preparation of a corrosion-resistant conductive composite coating for electrodes: A copper plate with dimensions of 50mm × 50mm × 1mm was used as the substrate and polished with 800-grit sandpaper until the surface roughness Ra was 1.0μm. The copper plate was then sequentially immersed in 100mL acetone, 100mL ethanol, and 100mL deionized water for ultrasonic cleaning for 15min each. After cleaning, the copper plate was dried in a 55℃ oven for 1.5h and cooled to room temperature to obtain a pretreated surface. 15g of the modified material prepared above was dispersed in a mixed solvent composed of 30g xylene and 20g n-butanol and ultrasonically treated at 400W for 40min. 100g epoxy resin, 0.5g leveling agent, and 0.3g defoamer were added, and the mixture was mechanically stirred at 1200rpm for 1h to obtain a uniform slurry. 40g polyamide curing agent was added under low-speed stirring at 300rpm, and stirring was continued for 15min to obtain the coating slurry. The coating slurry was uniformly sprayed onto the pretreated copper surface using a spray gun under a pressure of 0.3 MPa, with the wet film thickness controlled at 180 μm. After spraying, the coating was surface-dried at room temperature (25°C) for 20 min, and then placed in a forced-air oven for stepped curing: first cured at 82°C for 1 h, then the temperature was increased to 155°C at a rate of 2°C / min for 2 h. After curing, the coating was cooled to room temperature in the oven to obtain the final composite coating.

[0045] Comparative Example 1

[0046] The specific implementation method is the same as in Example 1, except that yttrium nitrate hexahydrate is not added during the preparation of the modified material; the remaining steps are exactly the same as in Example 1. Specifically, 2.0 g of titanium aluminum carbide is treated according to the method of Example 1 to obtain an aminated two-dimensional layered carbonitride. 5.0 g of 2,5-dihydroxyterephthalaldehyde and 3.8 g of 1,2-diaminocyclohexane are used to prepare a Schiff base ligand according to the method of Example 1, but without performing a yttrium coordination reaction. 1.0 g of the aminated two-dimensional layered carbonitride and 1.5 g of this Schiff base ligand (non-coordination compound) are assembled according to the method of Example 1 to obtain a comparative material. The coating preparation method is exactly the same as in Example 1, using 8.0 g of this comparative material.

[0047] Comparative Example 2

[0048] The specific implementation method is the same as in Example 1, except that unfunctionalized original two-dimensional layered carbonitrides are used instead of yttrium-functionalized two-dimensional layered carbonitrides / Schiff base two-dimensional heterostructure materials in the preparation of the modified material. Specifically, 2.0 g of titanium aluminum carbide is reacted with 100 g of 40% (w / w) fluorosulfonic acid aqueous solution at 35°C for 24 h. After centrifugation and washing, it is directly dispersed in N,N-dimethylformamide without amination or subsequent assembly reaction to obtain an original two-dimensional layered carbonitride dispersion. 8.0 g of this original material is used in the coating preparation, and the remaining steps are the same as in Example 1.

[0049] Comparative Example 3

[0050] The specific implementation method is the same as in Example 1, except that no modifying materials are added in the coating preparation. Instead, 100g of epoxy resin, 35g of polyamide curing agent, 0.5g of leveling agent, and 0.3g of defoamer are dispersed in a mixed solvent of 50g xylene and n-butanol. The remaining steps are the same as in Example 1.

[0051] Performance testing

[0052] The performance of Examples 1-3 and Comparative Examples 1-3 was tested according to the following method, which included the following steps: The corrosion resistance of the coating was evaluated by a neutral salt spray test. The coating sample was placed in a salt spray chamber and continuously sprayed with a 5wt% sodium chloride solution. The chamber temperature was maintained at a constant 35±1℃. The sample was placed at a 20° angle to the vertical direction. The surface condition of the coating was observed and recorded every 24 hours for a total of 1000 hours. Electrochemical impedance spectroscopy was performed using an electrochemical workstation. The sample was immersed in a 3.5wt% sodium chloride solution for 24 hours before testing. The frequency scan range was from 0.01Hz to 100kHz. A sinusoidal signal with an amplitude of 10mV was applied, and the test was conducted at an open-circuit potential. Parameters such as coating resistance and charge transfer resistance were obtained through equivalent circuit fitting, with particular attention paid to the impedance modulus at 0.01Hz. Conductivity was measured using a four-probe tester. At 25±1℃, the probe spacing was set to 1mm. Five different locations were uniformly selected on the sample surface for measurement, and the average value was used to calculate the surface resistivity. Adhesion testing employed the pull-off method, using a 20mm diameter aluminum alloy ingot. The ingot was bonded to the coating surface with a two-component epoxy structural adhesive. After curing at 25℃ for 24 hours, an adhesion tester was used to apply a uniform tensile force at a rate of 0.2MPa / s. The maximum force at which the coating detached was recorded, and the adhesion strength was calculated. Impact resistance testing used an impact testing machine equipped with a 1kg hammer. The hammer was dropped freely from a height of 50cm onto the coating surface. The impact head diameter was 8mm. Cracks or peeling were checked for. Coating thickness was measured using an eddy current thickness gauge. Ten measurement points were selected on the sample surface using a grid method, and the average value was taken as the final thickness. All tests were conducted under standard environmental conditions of 25±1℃ and 50±5% relative humidity. Each sample was tested in triplicate, and the average value was taken as the final result.

[0053] Test results:

[0054] Table 1: Test results of each embodiment and comparative example

[0055]

[0056] As shown in Table 1, Examples 1-3 of this invention successfully solved the technical problem that existing electrode coatings cannot simultaneously achieve high conductivity and long-term corrosion resistance. The surface resistivity of the coatings prepared in Examples 1-3 is all below 0.35 Ω·cm², and they remain intact after 1000 hours of testing in a high-concentration salt spray environment. Their low-frequency impedance modulus all exceed 10. 10 The conductivity (Ω·cm²) of Comparative Example 1 is significantly better than that of the comparative examples. Due to the lack of coordination by yttrium ions, Comparative Example 1, while maintaining a certain level of conductivity (1.25 Ω·cm²), exhibits a sharp decline in corrosion resistance, with an impedance modulus of only 5.6 × 10⁻⁶. 8 The results show that the unique structure of the yttrium-Schiff base complex plays an irreplaceable role in improving the corrosion resistance of the coating. Comparative Example 2 uses an unfunctionalized two-dimensional material with conductivity (15.60 Ω·cm²) and corrosion resistance (impedance modulus 3.2 × 10⁻⁶). 7 The surface resistivity (Ω·cm²) of Yttrium-functionalized two-dimensional heterostructure materials is severely insufficient, indicating that simple two-dimensional materials cannot construct an effective synergistic protection system. Comparative Example 3, without any functional fillers, has a surface resistivity exceeding 1000 Ω·cm² and completely lacks corrosion resistance, further confirming that the modified material of this invention is key to achieving both conductive and corrosion-resistant functions. More importantly, this invention achieves excellent performance through a simple spray-curing process, using commercially available raw materials, avoiding the complex high-temperature treatments or special equipment requirements of traditional processes, truly achieving a balance between high performance and low cost. This innovative design based on Yttrium-functionalized two-dimensional heterostructure materials successfully overcomes a long-standing technical bottleneck in the field of electrode coatings.

[0057] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for the preparation of a corrosion resistant electrically conductive composite coating for electrodes, characterized in that, Comprise the following steps: S1, sandpaper is used to polish the copper surface until the surface roughness Ra is 0.8-1.2 μm; then the copper is sequentially placed into acetone, ethanol and deionized water for ultrasonic cleaning; the cleaned copper is placed into an oven for drying, and cooled to room temperature to obtain a pretreated copper surface; S2, disperse the yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material in a mixed solvent composed of xylene and n-butanol, and ultrasonic treatment; Add epoxy resin, leveling agent and defoaming agent, stir to obtain a slurry, add polyamide under stirring, continue to stir to obtain a coating slurry; S3, the coating slurry is sprayed on the pretreated copper surface; After spraying, air dry at room temperature; S4, then put it into a forced air oven for step curing: first cure at 78-82℃, then heat to 145-155℃ for curing, after curing, cool to room temperature with the oven; The yttrium-functionalized two-dimensional layered carbonitride / Schiff base two-dimensional heterostructure material is prepared by the following method: A1, place titanium aluminum carbide in a reaction kettle, add an aqueous solution of fluorosulfonic acid, and stir at 34-36℃; after the reaction is completed, wash by centrifugation, collect the precipitate, disperse the precipitate in N,N-dimethylformamide again to obtain a dispersion liquid, add 3-aminopropyltriethoxysilane to the dispersion liquid, reflux at 58-62℃, centrifuge, and vacuum dry to obtain aminated two-dimensional layered carbonitride; A2, dissolve 2,5-dihydroxyterephthaldehyde and 1,2-diaminocyclohexane in anhydrous ethanol respectively to obtain an aldehyde solution and an amine solution, add the amine solution dropwise to the aldehyde solution under nitrogen protection, heat to 68-72℃ after dropwise addition is completed, and react to obtain a Schiff base ligand; mix the Schiff base ligand with yttrium nitrate hexahydrate in an acetonitrile / ethanol mixed solvent, add triethylamine, and stir at 78-82℃; after the reaction is completed, rotary evaporation, wash with diethyl ether, and vacuum dry to obtain a yttrium-Schiff base complex; A3, disperse the aminated two-dimensional layered carbonitride in a mixed solvent of anhydrous ethanol and N,N-dimethylformamide again, and ultrasonic treatment to obtain a dispersion liquid; dissolve the yttrium-Schiff base complex in a mixed solvent of anhydrous ethanol and N,N-dimethylformamide, add dropwise to the dispersion liquid under stirring, and add sodium cyanoborohydride; continue to stir after dropwise addition is completed; after the reaction is completed, collect the solid product by centrifugation, wash the solid product with ethanol and deionized water alternately to obtain a washed solid product; A4, heat treat the washed solid product under a nitrogen atmosphere: heat to 195-205℃ and keep; heat to 345-355℃ and keep; obtain a product, grind the product into a powder, and sieve.

2. The method for the preparation of corrosion-resistant, electrically conductive composite coatings for electrodes according to claim 1, characterized in that, In step S1, the temperature for drying in the oven is 45-55℃.

3. The method for making a corrosion-resistant, electrically conductive composite coating for an electrode according to claim 1, characterized in that, In step S2, the ultrasonic treatment time is 30-40min.

4. The method of claim 1, wherein the method further comprises: In step S3, the air drying time at room temperature is 15-20min.

5. The method of claim 1, wherein the method further comprises: In step S4, the curing time at 78-82℃ is 1-2h; the curing time after heating to 145-155℃ is 2-4h.

6. The method of claim 1, wherein the method further comprises: In step A1, the refluxing time at 58-62℃ is 6-8h.

7. The method of claim 1, wherein the method further comprises: In Step A2, the reaction time is 8-10 h with stirring at 78-82 °C.

8. The method of claim 1, wherein the method further comprises: In Step A3, the stirring time is 24-30 h.

9. The method of claim 1, wherein the method further comprises: In Step A4, the temperature is raised to 195-205 °C for 2-4 h.

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