Challenging reinforced composite polymer electrolyte membranes based on disulfonated poly(arylene ether sulfone)-impregnated expanded PTFE for fuel cell applications

Abstract

An ultrathin, low cost and high performance reinforced composite membrane (20 μm, thick) based on disulfonated poly(arylene ether sulfone)-impregnated polytetrafluoroethylene (PTFE) for polymer electrolyte membrane (PEM) fuel cell application was investigated. For comparison, PTFE-reinforced Nafion^® membrane (Nafion/PTFE), pristine disulfonated poly(arylene ether sulfone) membrane (SPSU) and recast Nafion112 membrane (rN112) membrane were employed. The peak power density of a single PEM fuel cell employing the composite membrane (SPSU/PTFE) reached 2.4 W cm⁻², twice that of the rN112 membrane. The SPSU/PTFE membrane structure was characterized and confirmed by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The improved interface compatibilty of the two components in the SPSU/PTFE membrane, reflected by enhanced morphology/surface property, was ascribed to the surface pre-treatment of microporous expanded PTFE and the presence of the n-butanol auxiliary solvent in the membrane fabrication process. The excellent single cell performance employing our SPSU/PTFE membrane was attributed to the implementation of ultrathin PTFE-reinforced membrane with low areal resistance and utilization of a high proton conductive SPSU ionomer. Our SPSU/PTFE membrane might indicate or pave a way of fluorine-less or non-fluorinated ionomer membranes to replace Nafion^® membranes for PEM fuel cell applications.