Cold Start and Freeze/Thaw Cycles Effect on PEFMC Performances

Water production is one of the most interesting characteristic of Proton Exchange Membrane Fuel Cell (PEMFC). However it is also one of the most restricting points, especially for automotive application on winter conditions. In order to further assess the cold operating mechanisms and their effect on durability, specific aging experiments were performed on isothermal single cells. It was found that drying process itself, without start up at sub-zero temperature, can lead to significant degradations. Moreover, 140 freeze/thaw cycles of a fully hydrated MEA have little effect on the FC performances (0.004% cycle-1 at 0.5 A cm-2). Furthermore, successive cold starts with FC starving affect significantly the FC performances. Degradation rates are at least 100 times higher than the one obtained for successive freeze/thaw cycles applied of a non dried cell. This would mean that ice produced during cold start doesn't locate at the same place than the one produced during freeze/thaw cycles.