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

A gel polymer electrolyte based on poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) and poly(methyl methacrylate) (PMMA) as host polymers, lithium perchlorate (LiClO4) 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 303K to 343K. Addition of plasticizers to polymer blend electrolyte has been found to result in an enhancement of the ionic conductivity. A maximum electrical conductivity of 1.03x10-3Scm-1 at 303K has been achieved for the polymer blend gel electrolyte containing 60wt% 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.