CHARACTERIZATION OF POLYMER ELECTROLYTES FOR FUEL-CELL APPLICATIONS

We review here our recent work on polymer electrolyte fuel cells empha sizing membrane transport issues. Transport parameters measured at 30- degrees-C for several available perfluorosulfonic acid membranes are c ompared. The diffusion coefficient and conductivity of each of these m embranes were determined as functions of membrane water content. Data on water sorption and conductivity are reported for an experimental me mbrane which is a modified form of NAFION(R). Contact angle measuremen ts indicate that the surface of a perfluorosulfonic acid membrane expo sed to water vapor is quite hydrophobic, even in the presence of satur ated water vapor. Modeling of water distribution in PEFCs based on the uptake and transport data shows that membrane thickness contributes i n a nonlinear fashion to performance in PEM fuel cells.