Effect of PC:DEC plasticizers on structural and electrical properties of PVDF–HFP:PMMA based gel polymer electrolyte system

Abstract

A gel polymer electrolyte based on poly(vinylidene fluoride–hexafluoropropylene) (PVDF–HFP) and poly(methyl methacrylate) (PMMA) as host polymers, lithium perchlorate (${\hbox {LiClO}}_{{4}}$) as salt has been prepared with different concentrations of mixture of propylene carbonate (PC) and diethyl carbonate (DEC) (1:1) as plasticizers by using solution casting technique. Changes in structural properties have been studied by X-ray diffraction. Surface morphology has been analyzed using atomic force microscope studies. Electrical conductivity has been carried out by electrochemical impedance spectroscopy in the temperature range 303 K to 343 K. Addition of plasticizers to polymer blend electrolyte has been found to result in an enhancement of the ionic conductivity. A maximum electrical conductivity of $1.03 \times 10^{-3}$ S cm$^{-1}$ at 303 K has been achieved for the polymer blend gel electrolyte containing 60 wt$\%$ of PC:DEC plasticizers. The temperature dependence of the ionic conductivity exhibits Vogel–Tammann–Fulcher type behavior indicating a strong coupling between the ionic conductivity and the polymer chain segmental motions. AC conductivity has been analyzed using Jonscher’s power law. A relaxation phenomenon is studied with modulus formalism.