The study of ion transport parameters connected with Na+ ion dynamics in biopolymer electrolytes through electrical equivalent circuits: Dielectric and electrochemical properties

Abstract

Non-toxic materials including polymers and salts meet global demand for renewable energy and they are crucial to be considered in the energy storage application. In this study, the appropriateness of solid biopolymer electrolytes for energy storage applications is examined, as these materials have the potential to overcome the limitations of conventional liquid electrolytes. The solution casting method to generate membranes of ion-conducting polymer blend-based electrolytes from a methylcellulose-dextran (MC:DEX) blend mixed with sodium acetate (NaCH3COO) to act as an Na+ supply, and glycerol to serve as a plasticizer. The electrochemical impedance measurement is performed to determine several transport parameters, including density number (n), mobility (µ), and diffusion coefficient (D). The highest glycerol content resulted in an ionic conductivity of 8.87×10−5 S cm−1. Furthermore, the electrical properties of the electrolytes are investigated, including dielectric, AC conductivity and electric modulus parameters. The maximum plasticized system was found to have an ion transference number of 0.98, indicating that ions played a critical role in the charge transfer mechanisms. Linear sweep voltammetry analysis demonstrated the stability of the maximum conductive sample up to 2.3 V.