Contamination of Membrane-Electrode Assemblies by Ammonia in Polymer Electrolyte Fuel Cells

Experimental and computational investigation of contamination of polymer electrolyte fuel cell (PEFC) membranes and catalyst layers with ammonia (NH3) is reported. Cyclic voltammetry (CV) scans and electrochemical impedance spectroscopy (EIS) analyses show that trace amounts of ammonia can significantly contaminate both the polymer electrolyte membrane (PEM) and the catalyst layers. The results show that the catalyst layer contamination can be reversed under certain conditions, while the membrane recovery tends to be much slower, and permanent effects of ammonia contamination is observed. A model is also developed to predict the degradation of the cell performance due to the decrease in membrane conductivity. The model incorporates Nernst-Planck equations to represent the multi-component cationic transport across the membrane, which helps differentiate between the degradation due to internal resistance and contamination of the catalyst layers. Mechanisms of contamination of the polymer electrolyte and catalyst layers, and performance degradation of the PEFC are also postulated.