Proton Conductivity of Graphene-Based Polymer Electrolyte Membrane

Abstract

A polymer electrolyte membrane fuel cell (PEMFC) is the one of promising alternative energy systems, however, the one of bottlenecks of the PEMFC performance is a poor key transport property, e.g., proton conductivity in catalyst layers. Recently, it has been reported that the addition of a rapidly emerging material, i.e., graphene, to the catalyst layer significantly improves the performance, but the understandings of the role of the graphene on the performance improvements are limited so far. The graphene-based PEM, i.e., Nafion®, is coated on the bulk Nafion® membrane, and the proton conductivity is measured using an impedance spectroscopy with respect to the graphene content from 0 to 3 wt% at the ambient temperature and liquid-water equilibrated state. It shows the proton conductivity enhancement with the increasing graphene content. The proton conductivity is compared using those of the carbon black (CB)- and carbon nanotube (CNT)-based PEM, showing that graphene-based PEM provides greater enhancement. The results suggest that the unique structures of the graphene could improve the proton conducting pathways within PEM. The obtained results provide an insight into an optimal material for improving the proton transport of PEM.