Preparation, characterization and single cell testing of new ionic conducting polymers for fuel cell applications

In this work, heterogeneous sulfonation and both, structural and electrical characterization of a mixture composed on block copolymer ionomers (HSBS and EPDM)and commercial silica, are studied. The incorporation of sulfonic groupswas checked by infrared spectroscopy (FTIR-ATR). Microstructurewas studied by means of dynamic mechanical analysis (DMA). Also,water uptake and methanol crossoverwere determined, and the results were compared with those of Nafion® 117. Electrical behavior was recorded by means of electrochemical impedance spectroscopy (EIS)at different hydration times. Results show that sulfonation of the styrene rings has effectively occurred. Conductivity values are similar to Nafion and they improve with hydration time. Methanol crossover is lower than in Nafion. Finally, a single complete proton exchange membrane fuel cell (PEMFC)as a wholewas tested obtaining the polarization and power curves at different temperatures and pressures, and modeling it by an electrical equivalent circuit (EC)in the symmetrical mode (SM)configuration using the EIS technique. This study offers a physical interpretation relating physical parameters to several processes occurring in the system. Power density values are higher than in Nafion.