Effect of polymer blending on the electrochemical properties of porous PVDF/PMMA membrane immobilized with organic solvent based liquid electrolyte

In this paper, experimental studies on blend gel polymer electrolyte membranes comprising of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) saturated with 0.1 M liquid electrolyte of sodium tetrafluoroborate (NaBF4) in the mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) are presented. Membranes are prepared by phase inversion technique. The effect of blending on the ionic conductivity, electrochemical stability window, ionic transference number, and cation transport number has been investigated using complex impedance spectroscopy, linear sweep voltammetry and DC polarization technique. Ion dynamics in the electrolyte membranes has also been investigated using dielectric studies. The optimized electrolyte membrane with composition PVDF:PMMA (95:5) + 0.1 M NaBF4 + EC + DEC shows highest ionic conductivity of 0.6 mS cm(-1) which follows Vogel-Tamman-Fulcher (VTF) behavior with temperature. The membrane shows an electrochemical stability window of 3.5 V and sodium ion transport number as similar to 0.33.