Physicochemical properties of proton conducting membranes based on ionic liquid impregnated polymer for fuel cells

Polymer electrolyte membranes containing a room temperature ionic liquid, 2,3-dimethyl-1-octylimidazolium triflate (DMOImTf) in polyvinylidenefluoride-co-hexafluoropropylene (PVdFHFP), show conductivity of 0.96x10(-3) S cm(-1) at 80 degrees C. The addition of triflic acid (HCF3SO3) increases the conductivity of the polymer electrolytes by providing free H+ ions, which is important for their potential use in proton exchange membrane fuel cells (PEMFCs) and other electrochemical devices. Line narrowing observed in the variation of H-1 and F-19 NMR line width with temperature shows that both protons and anions are mobile in these electrolytes. The membranes have been found to be thermally stable up to 200-300 degrees C. Polymer electrolyte membranes containing the ionic liquid have also been tested in a single cell fuel cell under non-humid conditions and found to be electroactive for hydrogen oxidation and oxygen reduction at platinum electrodes.