Preparation procedure for the electrode slurries of polymer electrolyte fuel cells utilizing the irreversibility of ionomer adsorption onto Pt-C particles

The effect of slurry preparation for polymer electrolyte fuel cells on the electrode performance has been investigated in this work. The amount of ionomer adsorbed onto Pt-C powder increases when water is used as a solvent; however, the size of non-adsorbed ionomer particles increases as well, resulting in a larger gas permeation resistance. Meanwhile, increasing the ethanol-to-water mass ratio in a mixed solvent decreases the ionomer size. Therefore, an improved two-step slurry preparation procedure utilizing the irreversibility of the ionomer adsorption onto Pt-C powder has been investigated. In this method, (1) Pt-C powder is mixed with ionomer in water to maximize its adsorbed fraction, after which (2) ethanol is added to the prepared slurry to minimize the size of non-adsorbed ionomer. As compared with the conventional one-step synthesis method, the developed two-step preparation procedure enhances the electrode performance without changing its composition. (C) 2019 The Ceramic Society of Japan. All rights reserved.