Performance and Durability of Membrane Electrode Assemblies Based on Radiation-Grafted FEP-g-Polystyrene Membranes

Membrane electrode assemblies (MEAs) based on radiation-grafted proton exchange membranes developed at PSI have shown encouraging performance in the past in hydrogen and methanol fuelled polymer electrolyte fuel cells. In this study, the effect of the pre-treatment of crosslinked radiation-grafted FEP membranes prior to lamination with the electrodes on the performance of the MEAs was investigated. Two approaches were assessed separately and in combination: (1) the impregnation of the radiation-grafted membranes with solubilised Nafion (R), and (2) the use of a swollen vs. dry membrane. It is found that the combination of coating the membrane with Nafion (R) ionomer and hot-pressing the MEN with the membrane in the wet state produce the best single cell performance. In the second part of the study, the durability of an MEA, based on a radiation-grafted FEP membrane, was investigated. The performance was stable for 4 000 h at a cell temperature of 80 degrees C. Thera, a notable degradation of the membrane, as well as the electrode material, started to occur as a consequence of either controlled or uncontrolled start-stop cycles of the cell. It is assumed that particular conditions, to which the cell is subjected during such an event, strongly accelerate materials degradation, which leads to the premature failure of the MEA.