High efficiency direct methanol fuel cell based on poly(styrenesulfonic) acid (PSSA)-poly(vinylidene fluoride) (PVDF) composite membranes

semi-Interpenetrating polymer network (sIPN) composite membranes consisting of poly(styrenesuflonic) acid (PSSA) and poly(vinylidene fluoride) (PVDF) have been prepared and evaluated as proton exchange membrane electrolytes in direct methanol fuel cells (DMFCs). The membranes fabricated were evaluated in terms of their proton conductivity, methanol permeability, and their performance characteristics in direct methanol fuel cells (DMFCs). PSSA-PVDF membranes demonstrated decreased methanol crossover during operation of direct methanol fuel cells compared to state-of-art Nafion^®-H membranes, yielding improved efficiency. PSSA-PVDF membranes have been demonstrated to operate efficiently in 1 in. × 1 in. and 2 in. × 2 in. direct methanol fuel cells. Fuel cells operating with PSSA-PVDF membranes were observed to have dramatically lower crossover rates compared to Nafion^® 117 systems. Greater than 95% reduction in crossover was observed in some cases. These properties of PSSA-PVDF membranes resulted in improved fuel performance and fuel cell efficiencies for direct methanol fuel cells. It was also observed that the PSSA-PVDF membranes behave quite differently compared with Nafion^®-based systems in terms water management characteristics at the cathode. The best performance with the new membranes was observed with very low oxygen or air flow rates at the cathode which is in contrast to Nafion^®-based systems, which generally require higher flow rates due to excessive water accumulation at the cathode, resulting in flooding.