Ultrasonic Spray Coating for PEM Fuel Cell

Ultrasonic Spray Coating Technique for High-Performance PEM Fuel Cell Electrode Manufacturing

The fabrication technique of membrane electrode assembly (MEA) significantly affects the performance and durability of proton exchange membrane (PEM) fuel cell. In the present study, ultrasonic spray coating technique has been used for manufacturing different sizes of gas diffusion electrodes up to 400 cm2. The catalyst ink was composed of 70 wt% catalyst and 30 wt% Nafion in a solution of 1:7 water to 2-propanol. The platinum loading of the electrode has been adjusted to 0.4 mg Pt/cm2. Commercial Pt/C catalysts have been used having different platinum content. Catalyst ink has been sprayed onto the gas diffusion layer using an ultrasonic spray coating instrument operating at 48 kHz. Coating process was fully computer controlled, and it was programmed according to the coating area, spray flow rate, and multiple layer coating. The performance of electrodes has been tested in a single PEM fuel cell. The power densities reached with the new method were 0.53, 0.74, 0.77, and 0.88 W/cm2 for 20, 40, 50, 70 % Pt/C catalyst by keeping the platinum loading constant, respectively. The power density increased 2.5 times compared to “spraying of catalyst ink with air pressure atomizing spray gun”. Uniform thin film has been achieved with ultrasonic coating method. Multiple layer formation retained the porosity of the electrode, impeded flooding on the electrode surface during the coating process, and enhanced transport of reactant during the fuel cell operation. Therefore, high-performance, reproducible, and large area electrodes could be manufactured by ultrasonic spray coating technique.