PEM fuel cells operated at 0% relative humidity in the temperature range of 23-120 °C

Operation of a proton exchange membrane (PEM) fuel cell without external humidification (or 0% relative humidity, abbreviated as 0% RH) of the reactant gases is highly desirable, because it can eliminate the gas humidification system and thus decrease the complexity of the PEM fuel cell system and increase the system volume power density (W/l) and weight power density (W/kg). In this investigation, a PEM fuel cell was operated in the temperature range of 23-120 °C, in particular in a high temperature PEM fuel cell operation range of 80-120 °C, with dry reactant gases, and the cell performance was examined according to varying operation parameters. An ac impedance method was used to compare the performance at 0% RH with that at 100% RH; the results suggested that the limited proton transfer process to the Pt catalysts, mainly in the inonomer within the membrane electrode assembly (MEA) could be responsible for the performance drop. It was demonstrated that operating a fuel cell using a commercially available membrane (Nafion^® 112) is feasible under certain conditions without external humidification. However, the cell performance at 0% RH decreased with increasing operation temperature and reactant gas flow rate and decreasing operation pressure.