Effect of air contamination by sulfur dioxide on the high temperature PEM fuel cell

Kurzfassung

High temperature PEM fuel cells (HT-PEMFCs) are attractive for applications from mobile to stationary fields and are characterized by enhanced tolerances against impurities like carbon monoxide. In this study, consequences of SO2-contaminated air were investigated systematically during 500 h of operation. After supplying 10 ppm SO2 the cathode was evidenced to be exposed to a stronger acidic environment. The bipolar plate showed an acid uptake in the gas outlet region 8 times higher than inside an uncontaminated cell. Furthermore, electrochemical oxidation of SO2 to SO42- was revealed. The catalyst showed a 5 times larger growth of Pt nanoparticles than the reference catalyst of the uncontaminated cell being attributed to larger Pt dissolution at lower pH. Although the cell showed good performance during 500 h, cell components were exposed to more corrosive conditions in presence of SO2. Last, the poisoning was shown to linearly decrease the voltage with decreasing temperatures.