Real world polymer electrolyte membrane fuel cell (PEMFC) applications will most probably use ambient air as the cathode oxidant.In addition to oxygen,the atmosphere may contain many impurities,which may have an adverse effect on fuel cell performance.Before the full-scale commercialization of fuel cell devices is possible,effects of different impurities must be determined and methods to mitigate the adverse effects found.In this contribution,the effects of sodium chloride were studied since it is present in the atmosphere in many fuel cell operating environments,especially coastal regions and near roads where NaCI is used as a de-icer during wintertime.The effect of NaCI on PEMFC performance was investigated by injecting NaCI solution into the cathode side air stream.The most significant effect of NaCI under test conditions is the replacement of H+ by Na+ in the ionomer of the catalyst layer.The presence of sodium ions not only affects the oxygen reduction kinetics but also lowers the protonic conductivity.In addition,NaCI was found to absorb into the graphite components of the cell,making them a long-term NaCI source.In contrast to expectations,chloride ions did appear to contribute to the cell performance loss.
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