Alkali doped polyvinyl alcohol/graphene electrolyte for direct methanol alkaline fuel cells

Abstract

Despite the intensive effort directed at the synthesis of anion exchange membranes (AEMs) only a few studies show enhanced ionic conductivity with simultaneous suppression of unfavourable mass transport and improved thermal and mechanical properties. Here we report an alkaline nanocomposite membrane based on fully exfoliated graphene nanosheets and poly(vinyl alcohol) (PVA) prepared by a simple blending process. The composite membrane shows improved ionic transport due to the homogeneous distribution of the graphene nanosheets which are able to form continuous, well-connected ionic channels. Significant enhancement of the ionic conductivity for the prepared graphene/PVA composite membranes is observed with a 0.7 wt% graphene loading resulting in a ∼126% improvement in ionic conductivity and a ∼55% reduction in methanol permeability. The resulting maximum power density obtained by incorporating the membrane in a cell is increased by ∼148%. A higher graphene loading (1.4 wt%) enhances the adhesion of the nanofiller–matrix, giving a ∼73% improvement in the tensile strength. This study provides a simple route to designing and fabricating advanced AEMs.