2018 Volume 126 Issue 10 Pages 789-793
Polybenzimidazole (PBI) electrolyte and TiO2-doped PBI electrolyte membranes were fabricated for application in intermediate temperature hydrogen fuel cells. These membranes and their assembled cells were characterized by field emission scanning electron microscopy, optical microscope, conductivity measurement, and fuel cell evaluation. Metal oxide particles have a high affinity for phosphoric acid. Hence, TiO2 was added to the PBI electrolyte membrane at various concentrations to increase the retention of phosphoric acid. The proton conductivity of the electrolyte membrane with TiO2 nanoparticles and their influence on the fuel cell power generation characteristics were investigated under anhydrous condition at 150°C. The TiO2/PBI electrolyte membrane achieved output characteristics more than twice that of the pure PBI electrolyte membrane. It was observed that the addition of TiO2 improved the phosphate holding power of the electrolyte membrane. TiO2/PBI membrane retained high conductivity values at the higher temperatures as a result of its high doping level and high water retention capacity. TiO2 (2 wt %)/PBI composite membrane showed the best performance with a power density of 434 mW cm−2. These results suggest that TiO2/PBI-based composite membranes are promising electrolytes for intermediate temperature polymer electrolyte membrane fuel cells.