Composite Graphene/Blended Polymer of PEO/PVDF-HFP As Solid Polymer Electrolyte for Sodium Batteries

Abstract

Solid polymer electrolytes (SPEs) are promising candidates for their application in electrochemical devices owing to its thermal and mechanical stability for application purposes [1-3]. The ionic conduction in polymer electrolytes occurs in amorphous phase where the ionic motion is coupled with the segmental motion above glass transition temperature. Among various polymers, the polyethylene oxide (PEO) has been studied extensively so far due to its high mechanical property and low barriers to bond rotation with ion efficiency [4,5]. Recently, the poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) has also greatly attracted as a polymer matrix with which provides mechanical stability (by PVdF) and improves ionic conductivity (by HFP component) [6-8]. In this work, we employed the blending polymer of PEO and PVdF-HFP to create a SPEs for sodium-ion battery application. Graphene addition aims to enhance ionic conductivity and mechanic properties of SPEs. Structure and morphology of polymer electrolytes were characterized by X-rays diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal properties of membrane were analyzed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Ionic conductivity and electrochemical stability of polymer membranes were also studied using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The battery performance was evaluated based on charge/discharge curve and sodium intercalation/deintercalation process. A comparison between Na-ion and Li-ion battery using SPEs was also performed.