Research on Ultrasonic Spraying Preparation Process and Application Fields of Functional Graphite Felt Coatings

Graphite felt, a porous flexible carbon material with high specific surface area, excellent electrical conductivity, high temperature resistance, and chemical stability, is widely used in several key fields such as electrochemical energy storage, hydrogen production, and high-temperature protection. It is one of the indispensable core substrates in high-end equipment and new energy technologies. However, rudimentary graphite felt has inherent defects such as low surface activity, limited mechanical stength, poor interfacial compatibility, and susceptibility to corrosion and rapid performance degradation under specific working conditions (such as strong acids and alkalis, high-potential environments). These defects greatly limit its service performance and service life in high-end applications.

Common Coating Types for Graphite Felt

1. Carbon-based Coatings: Graphene, carbon nanotubes, etc.

Function: Improves the conductivity, mechanical strength, and corrosion resistance of graphite felt while maintaining its porous structure.

2. Metal Oxide Coatings: TiO₂, MnO₂, etc.

Function: Imparts catalytic activity and ion storage/transport capabilities to graphite felt; commonly used for electrode modification in electrochemistry.

3. Conductive Polymer Coatings: Polyaniline (PANI), etc.

Function: Enhances the electrochemical activity, flexibility, and environmental stability of graphite felt, and reduces interfacial contact resistance.

4. Functionally Modified Coatings: Hydrophilic/Hydrophobic Coatings

Function: Adjusts the surface wettability of graphite felt to adapt to different liquid-phase reaction systems;

Advantages of Ultrasonic Spraying Technology

● Compared to traditional spraying (air spraying, electrostatic spraying), immersion methods, and chemical vapor deposition (CVD), ultrasonic spraying offers the following advantages in graphite felt coating preparation:

● High coating uniformity and controllable pore size: Ultrasonic atomization produces micron-sized droplets with uniform particle size and controllable velocity, which can penetrate into the interfiber spaces of the graphite felt to form a uniformly thick film without clogging the porous structure, thus preserving the material's high specific surface area.

● High raw material utilization and cost savings: The atomization process involves no high-pressure airflow, resulting in less droplet splashing and a raw material utilization rate exceeding 80%, far higher than the 30%-50% of air spraying. It also allows the use of low-concentration precursor solutions, reducing waste of valuable raw materials (such as graphene and precious metal oxides).

● Low-temperature film formation, protecting substrate performance: Ultrasonic spraying is a non-thermal spraying process, requiring no high-temperature heat source. This avoids oxidation, grain growth, or structural collapse of the graphite felt at high temperatures, making it particularly suitable for the preparation of heat-sensitive coating materials (such as conductive polymers).

● Precisely adjustable coating thickness: Coating thickness can be precisely controlled from the nanometer to the micrometer level to meet the performance requirements of different scenarios.

● Strong process compatibility and flexible operation: It can spray various precursor systems such as solutions and suspensions; the spray head can be paired with an automated platform to achieve large-area, conveyor-based, roll-to-roll uniform spraying.

Application Areas:

1. Electrochemical Energy Storage

Application Scenario: Electrode substrate for lithium-ion batteries.

Core Value: After spraying with metal oxide or carbon-based coatings, the electrochemical activity and ion transport efficiency of graphite felt are significantly improved, resulting in a substantial improvement in battery energy efficiency and cycle life.

2. Fuel Cells and Water Electrolysis

Application Scenario: Gas diffusion layer in proton exchange membrane fuel cells (PEMFC), electrode for hydrogen production via water electrolysis.

Core Value: Spraying with hydrophilic/hydrophobic composite coatings can optimize the gas-liquid transport performance of the electrode; spraying with catalytic coatings (such as RuO₂, IrO₂) can reduce the oxygen evolution overpotential in water electrolysis.

The rapid development of the hydrogen energy industry is driving the demand for high-performance electrode materials, and the low cost and high uniformity advantages of ultrasonic spraying meet the requirements of industrialization.

Shanghai Yangmi's innovative ultrasonic spraying technology is a precision spraying process that uses ultrasonic vibration to achieve precise atomization of the solution. This process can produce functional coatings with uniform thickness, strong adhesion, and controllable pore structure. Its low-temperature film formation, precise control, energy saving, and environmental protection features are highly compatible with the porous and flexible structure and modification requirements of graphite felt.