Polybenzimidazole-membrane-based PEM fuel cell in the temperature range of 120–200 °C

Phosphoric acid-doped polybenzimidazole-membrane-based PEM fuel cells were tested in the temperature range of 120–200 °C, with ambient backpressure and 0% RH. AC impedance spectroscopy, surface cyclic voltammetry and fuel cell performance simulation were used to obtain the exchange current densities for the cathodic oxygen reduction reaction (ORR) and anodic hydrogen oxidation reaction (HOR) on platinum-based catalysts at such high temperatures. The activation energies for ORR, HOR and membrane conductivity were also obtained separately. The results showed that temperature significantly affects the charger transfer and gas (O2 and H2) diffusion resistances. The effect of O2 stoichiometry (STair) on fuel cell performance was also investigated. Increasing STair can effectively increase the O2 partial pressure in the feed air, leading to improvements in both the thermodynamics and the kinetics of the fuel cell reactions. In addition, it was observed that increasing STair could also improve the gas diffusion processes.