Polymer–ionic liquid nano-composites electrolytes: Electrical, thermal and morphological properties

Room temperature ionic liquid (IL): 1-methyl-3-hexylimidazolium imide (HxMImTFSI) has been synthesized showing a high conductivity value of 4.3 mS/cm at room temperature. Polymer electrolytes (PEs) have been developed by impregnating the RTIL in poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) matrix with different binary compositions which have different molecular weights. PE's that are synthesized with the polymer having an average molecular weight of 400,000 shows highest room temperature conductivity of 4.86 × 10−4 S/cm at room temperature for (3:7 weight ratio). The nano-composite polymer electrolytes (NCPEs) were prepared by dispersing nano-tubular titania in the PE. Thermal stability of the IL and NCPEs was investigated using TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetric) studies showing the stability of these electrolytes in excess of 250 °C. High ionic conductivity has been observed of the order of 10−4 S/cm at RT and 10−3 S/cm at 120 °C for NCPE having composition 3:7 ratio of polymer and IL and containing 2 wt% nano-tubular titania. SEM studies show that there is an improvement in the morphology of the NCPEs with the addition of nano-tubular titania.