Cell Performance Distribution in a PEMFC Stack during Contamination

A PEMFC stack was contaminated with 50 ppm propene in air. The average performance decreased by 243 mV until a steady state was reached. After the propene injection was interrupted, the average performance increased until a new steady state was attained that exceeded the initial value by similar to 6 mV. Propene contamination amplified the uneven cell performance distribution along the stack length. End cells showed a larger performance change than the other cells with respect to the pre-contamination phase of respectively 24 and 15 mV. The effect was ascribed to interactions between propene and the uneven temperature distribution. Propene contamination affects both oxygen reduction kinetics and mass transfer as revealed by impedance spectroscopy measurements.