Nanostructured electrolyte membranes based on zeotypes, protic ionic liquids and porous PBI membranes: Preparation, characterization and MEA testing

An innovative electrolyte membrane concept based on the synergic combination of randomly porous doped PBI membranes 80% in porosity containing H-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as intrinsic proton conductor and microporous ETS-10 coatings as diffusional barriers has been developed for High Temperature PEMFC applications. The preparation route, involving up to 5 different steps, has been carefully optimized based on the evaluated proton conductivity and durability properties in presence of humidity at temperatures above 150 °C. The proton/methanol transport selectivity values of the optimized nanostructured membranes at 50°, 100° and 150 °C clearly outperform dense PBI and Nafion counterparts used as references. Moreover, the H2 permeability values for both the optimized nanostructured electrolyte membrane and dense PBI are quite similar at the examined conditions; indicating the suitability of the preparation procedure in terms of fuel cross-over. Finally, the as prepared membranes have been validated in H2/O2 single cell under non humidified conditions up to 180 °C as a “proof of concept” demonstration.