Design of biodegradable polymer blend electrolytes with decoupled ion motion for EDLC device Application: Electrical and electrochemical properties

Abstract

In this work, plasticized polymer blend electrolytes (PBEs) that are flexible and have quasi-solid-state properties have been prepared using the casting technique. Herein, we present the manufacture and characterization of biopolymer blend electrolytes based on chitosan (CS) and polyvinyl alcohol (PVA) with decoupled ion motion for EDLC device applications. Electrochemical impedance spectroscopy (EIS) was utilized to analyze the dielectric and ion conduction properties of the produced PBEs. Lithium nitrate (LiNO3) salt was used as an ion provider for the host polymers. With an increase in glycerol plasticizer concentration, both ion conduction and dielectric properties were significantly enhanced. The Argand diagram established that conductivity relaxation dynamics (pure ionic relaxation) is dominant at higher plasticizer concentrations. The highest ionic conductivity of 1.707×10-4 S/cm was recorded for the host medium plasticized with 40 wt% of glycerol, and it has been used as a mediator in the EDLC fabrication. Linear sweep voltammetry (LSV) was used to validate the eligibility of the PBE in terms of stability, and it was shown that the film was stable up to 2.93 V. The dominancy of ions as the main carrier in the prepared electrolyte was confirmed using transference number measurement (TNM) analysis, with tion = 0.922. The CR2032 coin cell type EDLC with activated carbon electrodes and the most conductive PBE film had a significantly high specific capacitance of ∼ 33F/g through the cyclic voltammetry (CV) technique. The efficiency of the fabricated EDLC was remarkable, with an average of about 85% over 1000 cycles. Due to its high energy and power densities (4.5 Wh/kg and 1100 W/kg, respectively), this PBE system is well-suited for EDLC.