Effect of Al2O3 nanoparticles on ionic conductivity of PVdF-HFP/PMMA blend-based Na+-ion conducting nanocomposite gel polymer electrolyte

Abstract

In the present work, the effect of dispersion of Al2O3 nanoparticles on ionic conductivity of non-aqueous PVdF-HFP/PMMA blend-based nanocomposite gel polymer electrolyte system comprising liquid electrolyte of sodium trifluoromethanesulfonate is investigated. The ionic conductivity of the electrolyte increases maximum to ∼ 1.5 × 10−3 S cm−1 for the composition with 6 wt% Al2O3 nanoparticles. The optimized composition retains Vogel-Tamman-Fulcher (VTF) behavior in the temperature range from − 50 to 95 °C. The scanning electron micrography and x-ray diffraction studies reveal the uniform dispersion of Al2O3 nanoparticles in the porous structure of the nanocomposite gel polymer electrolyte and enhanced amorphicity of polymer matrix. The optimized electrolyte composition owns a sufficiently large electrochemical stability window of ~ 3.6 V with good sodium ion transference number. The optimized electrolyte is used in a prototype sodium battery cell, which shows an open circuit potential of ~ 2.5 V and first discharge capacity ~ 400 mA h g−1 followed by a capacity decline with cycling.