Directly deposited Nafion/TiO2 composite membranes for high power medium temperature fuel cells

Abstract

This work presents a simple production method for TiO₂ reinforced Nafion® membranes which are stable up to a 120 °C operation temperature. The novel TiO₂ reinforced membranes yield a maximum power density of 2.02 W cm⁻² at 120 °C; H₂/O₂; 0.5/0.5 L min⁻¹; 90% RH, 300/300 kPa_abs. This is 2.8 times higher than the highest power density for TiO₂ reinforced membranes so far published in literature. The described membranes even exceed the maximum power density of a commercial Nafion® HP membrane in an identical measurement setup at 100 °C and 120 °C. Compared to the commercial Nafion® HP membrane the maximum power density was increased by 27% and 9% at 100 °C and 120 °C, respectively. The membrane is manufactured by drop-casting a dispersion of Nafion® and TiO₂ nanoparticles onto both the anode and cathode gas diffusion electrodes. Furthermore pure Nafion® membranes manufactured by the same method had higher membrane resistances at temperatures >100 °C than TiO₂-reinforced Nafion® membranes.