Durability Analysis and Improvement of Modified Cathode Electrocatalyst to Operate PEFC Cell under Low Relative Humidity

The modification of cathode catalyst was effective to improve cell performance under low relative humidity. Here we report the stability of the modified cathode Pt catalysts under low RH. The time dependences of the cell voltage of fixed current density operation at 0.5 A cm -2 (H 2 / Air) under RH=31% were measured. The cell voltage drop with time was almost finished after 20 h. The cell voltage after 33 h was around 0.46 V by using modified cathode electrocatalyst (initial cell voltage was 0.53 V), on the other hand, the cell voltage dropped to 0.42 V only after 20 h by using unmodified one (initial cell voltage was 0.48 V). The time dependences of the cell voltage of fixed current density operation at 0.8 A cm -2 under RH=31% were also measured. In this case, the drop of cell voltage was continued in both catalysts throughout the operation.