Analysis on the freeze/thaw cycled polymer electrolyte fuel cells

Enhancement of system durability at the sub-freezing temperature is one of critical issues for the commercialization of polymer electrolyte fuel cell (PEFC) applications. In this work, effects of residual water at the sub-freeze condition on the gas diffusion layer (GDL)/membrane-electrode assembly (MEA) were investigated for the successful cold start-up of PEFC. The performance changes of MEAs were observed by 300 times of freeze/thaw (F/T) cycles with well designed single cell. The post analysis for the (−30 to 70) °C F/T cycled MEA were conducted. The gradual decreases of I–V performance were observed after the F/T cycle number of 70. About 0.4 mV/cycle of degradation at 1 A/cm2 could be obtained at the controlled operating conditions. The main cause of performance decrease was in the weakened adhesion between the electrodes and membrane interface. The SEM images as well as cell resistance changes directly supported the degradation reasons of cell performance in the freeze condition.