Performance enhancement of Na+ ion conducting porous gel polymer electrolyte using NaAlO2 active filler

Abstract

In this paper, we report the enhanced electrochemical characteristic performance of porous gel polymer electrolyte, due to dispersion of sodium aluminate (NaAlO2) active fillers in it. The salt solution consisting of, sodium perchlorate (NaClO4) dissolved in binary mixture of ethylene carbonate and propylene carbonate (EC:PC) was entrapped in poly(vinylidinefluoride-co-hexafluoropropylene) (PVdF-HFP) polymer matrix to obtain the micro-porous sodium ion conducting gel polymer electrolyte films by using the phase inversion technique. Small loading of the active NaAlO2 fillers in gel polymer electrolyte results in significantly improved ionic conductivity (σmax=0.68 mS cm−1 at room temperature), Na+ ion transference number (tNa+∼ 0.45) and electrochemical stability window (ESW ∼ 4.1 V). Dielectric studies have been performed to explore the ion dynamics in the electrolyte system. The Na-S prototype battery delivers maximum discharge capacities of ∼ 210, 139 and 51 mA h g−1 at drain currents of 0.10, 0.25 and 0.50 mA cm-2, respectively. The optimized electrolyte composition with high liquid retention, conductivity and transport properties can be utilized for upcoming sodium batteries operating at room temperature.