This paper reports a study on the understanding of the performance decrease mechanisms of polymer electrolyte fuel cells under critical operating conditions. In order to investigate the durability of perfluorosulfonate membranes at low humidification conditions, long-term fuel cell tests have been carried out. Results evidenced a strong effect of low relative humidity on the commercial polymer membrane lifetime. Prolonged dehydration of the membranes led to a decrease of the three-dimensional reaction zone due to the ionomer degradation in the catalytic layer and a continuous loss of material in the membrane evidenced by a thickness decrease. The last effect provoked a collapse of the electrode structure. © 2010 Springer-Verlag.

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