Materials ageing mechanisms in PEM fuel cells

As fuel cell technology matures and time scale to commercialization decreases, the need for a more comprehensive knowledge of materials ageing mechanisms is essential to attain specified lifetime requirements for applications. In this work, the membrane-electrode assembly (MEA) degradation of a 5 cell PEM stack was evaluated, during and after fuel cell ageing in extreme testing conditions. Cross sections of the membrane catalyst layers and gas diffusion layers were examined indicating that cathode thickness is considerably reduced as a result of ageing. Catalyst particles were found to migrate outwards and located on carbon backings. Fluoride release was considered an indicator of membrane degradation, quantified using an ion selective electrode at gases outlet. MEA degradation mechanisms are discussed