Hybnd inorganic-organic nanocomposite polymer electrolytes based on Nation and fluorinated TiO_2 for PEMFCs

摘要

In this report, three hybrid inorganic-organic proton-conducting membranes based on a novel fluorinated titania labeled TiO_2F dispersed in Nation were prepared. The mass fraction of TiO_2F nanofiller ranged between 0.05 and 0.15. The water uptake and the proton exchange capacity of the membranes were determined; the membranes were further characterized by TG, DMA and FT-IR ATR investigations. Finally, the hybrid membranes were used in the fabrication of membrane-electrode assemblies (MEAs), which were tested in operating conditions as a function of the back pressure and of the hydration degree of the reagents streams. It was demonstrated that, with respect to pristine recast Nafion, at 25%RH the MEA fabricated with the membrane including a mass fraction of TiO_2F equal to 0.10 yielded a higher maximum power density (0.206 W cm~(-2) vs. 0.121 W cm~(-2)). Finally, it was proposed a coherent structural model of this family of hybrid membranes accounting for both the properties determined from "ex-situ" characterizations and for the performance obtained from measurements in a single fuel cell in operating conditions.