Targeting improved DMFC performance

Improved DMFC performance through reduction in the extent of methanol crossover in the polymer electrolyte membrane is described. Introduction of a thin barrier layer of polybenzimidazole (PBI) at the Nafion®117 surface by screen printing is shown to reduce methanol permeability whilst maintaining proton conductivity at a level comparable to that of the parent material. Experimental trials using these Nafion®117/PBI composite films show improved DMFC performance; an increased working current density range of 42% combined with an increase in maximum power output of 46% over that of the parent material.