Graphene-based Proton Exchange Membrane (PEM) for Direct Methanol Fuel Cell (DMFC)

A. Paneri, G. Ehlert, H. Sodano, S. Moghaddam
University of Florida, US

Keywords: proton exchange membrane, graphene oxide, sulphonated graphene oxide

Summary:

Direct methanol fuel cell (DMFC) is the most promising type of fuel cell for portable applications. High energy density of methanol, facility of its storage, and its direct oxidation on the anode are the main reasons for the great potential of DMFCs. However, the existing DMFC membrane electrode assemblies (MEAs) deliver a low power density. At the heart of the problem are deficiencies of the existing MEAs that suffer from; a) slow kinetics of methanol electro-oxidation on anode, b) limited operating temperature, c) significant methanol permeation, particularly at high fuel concentrations, and d) high water permeation and cathode water congestion. A graphene-based PEM is attractive as it does not swell at elevated temperatures and high fuel concentrations thus enabling enhancement in DMFC power density due to improvements in kinetics and transport. Here, we report development of graphene-based PEMs. The first membrane is a graphene oxide (GO) PEM, which is synthesized from colloidal dispersion of GO. Improvising this membrane, we synthesized a sulphonated GO membrane by dispersing GO sheets in a PBI/N,N-dimethylacetamide (DMAc) solution. These membranes were cast by evaporating the DMAc solvent, followed by immersion in H3PO4. The proton conductivity of a 15-micron-thick self-standing membrane is similar to that of Nafion-117.