Effect of Dispersion Solvent in Catalyst Ink on Proton Exchange Membrane Fuel Cell Performance

The effects of dispersion solvents in catalyst ink on performance of the membrane electrode assembly (MEA) for proton exchange membrane fuel cell are studied. Dispersion solvents under examination are water, ethylene glycol, glycerin, propylene glycols, and methanol. These solvents cover a wide range property of dielectric constant, boiling points, and viscosity. We examine the rheology behaviors of catalyst ink prepared with these solvents. Both anode and cathode of the MEA are made by using doctor-blade method to spread catalyst ink onto the gas diffusion layers. The single cell with prepared MEA is measured by linear scanning voltammetry to evaluate the discharge characteristics, by cyclic voltammetry to evaluate catalyst utilization, and electrochemical impedance spectroscopy to evaluate internal resistance. A semi-empirical equation is use to analyze the voltage losses due to activation over-potential and internal resistance. We find that ethylene glycol was the best dispersion agent among organic solvents tested. The power density of the single cell is able to reach the maximum power density of 1,428 mA (mg Pt)-1 at hot-pressed temperature of 135 °C, and 1200psi for 90 seconds.