Impact of Micromolar Concentrations of Externally-Provided Chloride and Sulfide Contaminants on PEMFC Reversible Stability

Abstract

In this paper, we evaluate the reversible performance stability of 3M membrane electrode assemblies containing either Nanostructured Thin Film Catalyst (NSTFC) or carbon-supported Pt (Pt/C) electrodes. Micromolar concentrations of chloride and sulfide ions, provided via the humidification DI water, were found to cause rapid but highly recoverable performance loss. The impact of chloride on the decay rate depends strongly on catalyst type, surface area, and cell temperature. The effect of these externally-provided species remains for several hours after they are removed from the humidification streams. The performance loss due to these species is largely recovered through a special shutdown and restart procedure, where liquid water is injected into the cell as it cools to room temperature.