Analysis of Degradation Mechanisms and Durability Assessment of Graphene-Based MPLs for PEM Fuel Cells

Novel graphene-based microporous layers (MPLs) have been developed as a possible alternative to conventional carbon black-based MPLs aiming to enhance electrical performance and durability of PEM fuel cell systems. Graphene nanoplatelets (GNPs) have been used as carbonaceous conductive phase in the ink formulation for MPL due to their low electrical resistance, high surface area and mechanical stability. The novel MPLs exhibited more homogeneous and less cracked surfaces compared to MPLs containing carbon black. Such enhanced MPL surface resulted in a better electrical contact between MPL and fuel cell electrode and a consequent lower ohmic resistance. Moreover, chemical and mechanical accelerated stress tests were developed in order to evaluate durability of the prepared samples and the most detrimental degradation mechanism. Fresh MPLs showed very similar electrochemical behaviors in running fuel cells while GNPs-based MPLs proved to be more resistant against both stress factors than conventional ones.