ELECTROCHEMICAL CHARACTERIZATION OF PVDF-BASED PROTON CONDUCTING MEMBRANES FOR FUEL-CELLS

The electrochemical characterization of proton-conducting membranes pr epared by irradiation-induced grafting and subsequent sulfonation of P VDF films has been performed. In particular, measurements of the ionic conductivity, oxygen solubility and diffusion in the membranes are pr esented, as well as kinetic data for the oxygen reduction reaction in a membrane-platinum system and a simulation of the performance of thes e PVDF-g-PSSA membranes in a solid polymer electrolyte fuel cell using a micro-cathode technique. At sufficient degrees of grafting (> 40%) the conductivity reaches 0.1 Scm(-1), well above that of Nafron 117 (D uPont). The PVDF-g-PSSA membranes show lower solubilities and higher d iffusion coefficients of oxygen and a higher water uptake than Nafion 117. The microcathode measurements indicate that those PVDF-g-PSSA mem branes which have a conductivity higher than that of Nafion 117 may al so give improved performance in fuel cell conditions provided that the y have the necessary mechanical and chemical stability. (C) 1998 Elsev ier Science Ltd. All rights reserved.