Effect of SO2 Concentration and Relative Humidity on Contamination of Cathode and Anode in PEMFC

Abstract

Catalyst poisoning by the SO2 supply to proton exchange membrane fuel cells (PEMFCs) under open circuit voltage (OCV) and load operational conditions was examined using simultaneous monitoring of cell voltage and SO2 emissions from the cathode exhaust. Results show that cell voltage reduction is inversely proportional to the concentration of supplied SO2. Experiments with different relative humidity conditions and measurement of the electro-chemical surface area (ECSA) by cyclic voltammetry investigated considerable RH effects on contamination of anode electrodes. At OCV condition, anode contamination was observed with a decrease of RH condition; little poisoning existed in fully dried conditions. On the other hand, little poisoning occurred at load operational conditions.