Impacts of operating conditions on the recovery of proton exchange membrane fuel cells exposed to sulfur dioxide in an air stream

Abstract

Airborne SO2 contaminants compromise the performance of proton exchange membrane fuel cells (PEMFCs) due to the formation of strongly adsorbed S-containing species, mainly S0, on the cathode Pt surface and a lack of self-recovery in pure air. To restore PEMFC performance, we applied voltage cycling from 0.1 to 1.2 V vs. the potential at the anode and with the H2/N2 gas configuration. This induced cyclic voltammetry (CV) procedure was examined for PEMFC performance recovery after 13–14 h of cathode exposure to 5 ppm SO2 under different conditions. It was determined that the efficiency of CV-induced recovery depended on the operating temperature and current during contamination. The method recovered 99% of the performance after exposure to SO2 at 60 °C and a constant current of 0.6 A cm−2. An increase in the operating current and cell temperature favored the formation of strongly bonded S0 and catalyst degradation, so the performance recovery reached 95% for 60 °C and 1.0 A cm−2, 90% for 80 °C and 0.6 A cm−2, and 84% for 80 °C and 1.0 A cm−2. The PEMFC performance after exposure to SO2 at high temperature could not be fully recovered by the CV-induced method and seemed to require additional or modified procedures.