The Influence of Fe Ion Emission from Metal Bipolar Plates on PEFC Performance

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It is known that Fe ion emission from bipolar plate materials reduces proton conductivity and accelerates the degradation of the electrolyte membrane. In this study, we investigated the influence of cell operating conditions on Fe ion emission from S65C carbon steel, used for the anode bipolar plate, under two kinds of power generation conditions. The effects of Fe ions emitted from the bipolar plate on cell performance were also investigated. The results showed that the bipolar plate corroded significantly under a continuous low current condition. It was found that the degradation of the electrolyte membrane was dependent on not only the quantity of Fe ion emission but also the humidity in the cell. Degradation of the electrolyte membrane occurred at a lower level of Fe ion emission than the previously reported results of ex-situ tests. We conclude that controlling the cell operating conditions and increasing the thickness of the gas diffusion layer (GDL) are effective measures for reducing the degradation rate of the electrolyte membrane.