The Multiprocess Degradation of PEMFC Performance Due to Sulfur Dioxide Contamination and Its Recovery

The effects of trace concentrations of contaminant present in the cathode feed stream on proton exchange membrane fuel cell (PEMFC) performance are studied. Contaminant concentrations of 1, 2, and 10 ppm were exposed to the cell applying a total dosage of of at and a current density of . All experiments show significant cell performance degradation before the steady-state poisoning state is reached. The performance degradation shows an inflection in the cell voltage, which is attributed to at least two different poisoning processes. The overall poisoning process is shown to consist of an irreversible part and a reversible part. While the performance loss of the reversible part is dependent on the concentration and is recoverable during a operation, that of the irreversible part is greatly recoverable by potential cycling in the mode. Evidence is also presented that cathode exposure to results in a performance impact at the anode. Furthermore, sulfur species that remain in the membrane electrode assembly accelerate the cell performance degradation during a neat operation and subsequent contaminant exposure.