A comparative study of different redox additive based gel polymer electrolyte for supercapacitor application

Abstract

This study describes the fabrication oh high energy density supercapacitors (SCs) employing activated carbon (AC) electrodes and gel polymer electrolytes (GPEs) based on redox additives. Adiponitrile was used as a plasticizer, 1-Butyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide (BMIMTFSI) as an ionic liquid (IL), potassium Iodide (KI), Caesium Iodide (CsI), and rubidium iodide (RbI) as redox additives, and poly(vinylidene fluoride-co-hexafluoropropylene) as the host polymer to create the GPEs. The amorphous character of the host polymer matrix was increased by plasticizers, redox additives, and ILs, according to the microstructural studies. Up to about 200 °C, the GPEs remained thermally stable. The redox additive-based GPE-KI has an electrochemical potential window of 6.38 V and an electrical conductivity of 3.3 × 10−3 S cm−1 at ambient temperature. Electrochemical impedance spectroscopy, galvanostatic charge-discharge, and cyclic voltammetry were used to examine the electrochemical performance of the SCs made with the dual redox additive-based GPEs and AC electrodes. Good cyclic performance was also demonstrated by the redox additive-based GPEs in specific capacitance, with an initial 34% fading and a about 100% sustained Coulombic efficiency over 5000 cycles.