Enhancement in electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes by 100 MeV Si⁹⁺ swift heavy ion irradiation

Abstract

Swift heavy ion (SHI) irradiation has been used as a tool to enhance the electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes dispersed with dedoped polyaniline (PAni) nanorods; 100 MeV Si⁹⁺ ions with four different fluences of 5 × 10¹⁰, 1 × 10¹¹, 5 × 10¹¹, and 1 × 10¹² ions cm⁻² have been used as SHI. XRD results depict that with increasing ion fluence, crystallinity decreases due to chain scission up to fluence of 5 × 10¹¹ ions cm⁻², and at higher fluence, crystallinity increases due to cross-linking of polymer chains. Ionic conductivity, electrochemical stability, and dielectric properties are enhanced with increasing ion fluence attaining maximum value at the fluence of 5 × 10¹¹ ions cm⁻² and subsequently decrease. Optimum ionic conductivity of 1.5 × 10⁻² S cm⁻¹ and electrochemical stability up to 6.3 V have been obtained at the fluence of 5 × 10¹¹ ions cm⁻². Ac conductivity studies show that ion conduction takes place through hopping of ions from one coordination site to the other. On SHI irradiation, amorphicity of the polymer matrix increases resulting in increased segmental motion which facilitates ion hopping leading to an increase in ionic conductivity. Thermogravimetric analysis (TGA) measurements show that SHI-irradiated nanocomposite polymer electrolytes are thermally stable up to 240–260 °C.