Novel hybrid proton exchange membrane electrolytes for medium temperature non-humidified fuel cells

New composite membranes consisting of phosphosilicate (P2O5-SiO2) content and 1 -ethyl-3 methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid were fabricated by sal-gel process. For all the prepared hybrid membranes, the interaction between the doped hydrophilic [EMIMBF4] ionic liquid and the inorganic phosphosilicate network was investigated by Fourier transform infrared spectroscopy. Average pore sizes and specific surface areas were investigated by the Brunauer-Emmett-Teller (BET) method. Thermogravimetry (TG) and differential thermal analysis (DTA) measurements confirmed that the hybrid membranes were thermally stable up to 220 degrees C. Relatively a high conductivity of 1 x 10(-2)S/cm (8.9 x 10(-3)S/cm for 40 wt% IL doped 60TMOS-30VTMOS-10PO(OCH3)(3) (mol%) hybrid membrane) was obtained for 40 wt% IL doped 30TMOS-30TEOS-30MTEOS-10PO(OCH3)(3) hybrid membrane, at 155 degrees C under anhydrous conditions. The hydrogen permeability was found to decrease within the range 10(-11) to 10(-12) mol/cm s Pa for 40 wt% IL doped membranes as the temperature increases from 20 to 150 degrees C. (C) 2010 Elsevier B.V. All rights reserved.