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

An ultrathin, low cost and high performance reinforced composite membrane ( 20 mm, 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(R) 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 22, 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(R) membranes for PEM fuel cell applications.