Ionic liquid-polymer gel electrolytes

New rubbery gel electrolytes have been prepared from room temperature ionic liquids and poly(vinylidene fluoride)-hexafluoropropylene copolymer [PVdF(HFP)]. The ionic liquids employed in these preparations were 1-ethyl-3-methylimidazolium salts of triflate (CF3SO3-) and BF4-. When properly processed, the ionic liquid-PVdF(HFP) gels are freestanding, flexible films with room temperature conductivities ranging from 1.1 to 5.8 mS cm(-1). Because both the ionic liquids and the PVdF(HFP) are nonvolatile and are thermally stable, the gels can be operated at elevated temperatures without performance degradation. An ionic conductivity of 41 mS cm(-1) was measured for a triflate ionic liquid-PVdF(HFP) gel at 205 degrees C.