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

Research highlights: → New composite membranes consisting of phosphosilicate (P2O5-SiO2) content and 1-ethyl-3 methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid were fabricated by sol-gel process. → 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 deg. 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 deg. C. → The prepared IL doped hybrid membranes are suitable for potential use in proton exchange membrane fuel cells (PEMFCs) at medium temperatures (100-150 deg. C) under non-humidified conditions. - Abstract: New composite membranes consisting of phosphosilicate (P2O5-SiO2) content and 1-ethyl-3 methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid were fabricated by sol-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 deg. 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 deg. 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 deg. C.