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Abstract:
In the present article, an ionic liquid-based polymer gel electrolyte was synthesized by using poly(vinylidene fluoride-co-hexafluo-ropropylene) (PVdF-HFP) as a host polymer. The electrolyte films were synthesized by using the solution casting technique. The as-prepared films were free-standing and transparent with good dimensional stability. Optimized electrolyte films exhibit a maximum room-temperature ionic conductivity of σ = 8.9 × 10^−3 S·cm^−1. The temperature dependence of the prepared polymer gel electrolytes follows the thermally activated behavior of the Vogel–Tammann–Fulcher equation. The total ionic transference number was ≈0.91 with a wider electrochemical potential window of 4.0 V for the prepared electrolyte film which contains 30 wt % of the ionic liquid. The optimized films have good potential to be used as electrolyte materials for energy storage applications.

Keywords:
ionic liquid, polymer gel electrolytes, solution casting technique, transference number

Abstract:
In the present study sodium ion conducting polymer blend electrolytes has been prepared using poly (vinylidene fluoride – hexafluoro – propylene) (PVdF-HFP), poly (methyl methacrylate) (PMMA), and sodium thiocyanate (NaSCN) salt by solution-cast technique. The highest ionic conductivity of the optimized blend polymer electrolyte system [PVdF(HFP)-PMMA (4:1)] (20 wt%)-[NaSCN (1 M)] (80 wt%) has been found to be 4.54 × 10^−2 S cm^−1 at room temperature. The temperature dependence conductivity plot shows the Arrhenius behaviour and its activation energy calculated from the plot were found to be 0.13 eV. The structural and morphological studies of polymer blend electrolyte were investigated by XRD, SEM and FTIR spectroscopy. Complex formation between polymer and salt has been confirmed by these studies. The thermal properties of optimized electrolyte system were examined by differential scanning calorimetry (DSC) techniques. The ionic transport number was calculated using d.c polarization techniques and was found to be 0.92, which shows that electrolyte system is predominantly ionic in nature. The electrochemical potential window of optimized polymer blend electrolyte was tested and observed to be ~2.8 V.

Keywords:
polymer blends electrolyte, solution cast technique, sodium ion, FTIR, DSC