Structure and Electrical Properties of Polymer Electrolyte Based on Plasticized Chitosan Grafted Polymethyl Methacrylate (Ch-g-PMMA)-Magnesium Triflate for Electrochemical Double Layer Capacitor

Abstract

Polymer electrolytes have received much attention as materials used in batteries, supercapacitors, sensors and solar cells. Most of the polymer electrolytes reported are based on synthetic polymer, therefore it is difficult to recycle as it has poor degradability and ends up being a waste. In recent years, biopolymers gained much interest in replacing environmentally unfriendly polymers. Various studies have been done to accomplish polymer electrolytes with high conductivity and long-term safety. This study’s objective is to prepare plasticized Ch-g-PMMA-based polymer electrolyte by introducing the magnesium triflate salt and glycerol plasticizer. The grafted polymer of Ch-g-PMMA was prepared using gamma (γ) radiation. The grafted polymer of Ch-g-PMMA with 0.4 g of Mg(Tf)2 and different concentrations of glycerol has been prepared by using the solution casting technique. To achieve this study, the prepared plasticized Ch-g-PMMA-Mg(Tf)2 polymer electrolytes are characterized by XRD, FTIR, EIS and LSV techniques. XRD was carried out to determine the change in crystallinity and the amorphous structure of the plasticized Ch-g-PMMA-Mg(Tf)2 polymer. FTIR reveals the occurrence of complexation between Ch-g-PMMA polymer, Mg(Tf)2 salt and glycerol plasticizer. The grafted Ch-g-PMMA-Mg(Tf)2 was added with different concentrations of glycerol from 0 to 50 wt%. The Ch-g-PMMA-Mg(Tf)2 polymer electrolyte with 50 wt% of glycerol shows the highest ionic conductivity of 1.50×10−4 S·cm−1 compared with other samples. The increase in mobility of ions and the number of charge carriers has enhanced ionic conductivity. Based on the LSV analysis, the highest conducting Ch-g-PMMA-Mg(Tf)2 polymer with 50 wt% of glycerol was found electrochemically stable up to 3.2 V. The goal of this study is to determine the structure and electrical properties as well as the window stability of plasticized Ch-g-PMMA-Mg(Tf)2. The best outcome was produced by adding the 50 wt% of glycerol into the Ch-g-PMMA-Mg(Tf)2 which increased further by 1 order of magnitude.