Investigation of ion and water transport mechanisms in perfluorosulfonated ionomer membranes for fuel cells

Abstract

In order to clarify the transport mechanisms of ions and water molecules in perfluorosulfonated ionomer membranes, various membranes, such as a Nafion, two Aciplex and four Flemion types, having different equivalent weight values (EW) were examined. H, Li and Na-form samples were prepared for each membrane by immersing in 0.03 M HCl, LiCl and NaCl aqueous solutions, and their properties in the fully hydrated state were investigated systematically. The water content, ionic conductivity, water transference coefficient, water permeability and self-diffusion coefficient of water and Li+ for the membranes were measured, and the mutual relationships between the structure of membranes, the ion-exchanged cations and the transport behaviors of the cations and water molecules in the membranes are discussed.