Materials Synthesis Characterizations Device Fabrication and Performance Evaluation of Spinel Cobaltites Based NanocomPosite Electrodes for Supercapacitor Application

Abstract

Supercapacitors are considered one of the emerging technologies for electrochemical energy storage devices. These are renowned for providing higher power density than batteries and more energy density than traditional capacitors. On the way to improving their energy density comparable to batteries while maintaining the power density, nanostructured electrode materials are being widely explored. Materials mainly metal oxides, conducting polymers, and carbon-based are choices for the fabrication of supercapacitor electrodes. However, apart from using them in their pristine form, their composites or hybrids are of more importance due to the synergistic contribution of all individual components. The electrode materials optimized based on morphology, dimensions, and porosity result in the high electrochemical performance of supercapacitors. Single metal oxides possess good redox behavior and are naturally abundant but suffer from inferior electrochemical stability and conductivity. In this domain, mixed transition metal oxides (MTMOs) such as NiCo2O4, CoMn2O4, NiMn2O4, ZnCo2O4, and MnFe2O4 have dragged considerable attention as battery-type supercapacitor electrodes due to the presence of multiple oxidation states favorable for high energy storage. Also, their composites with conducting polymers, metal oxides, and carbonaceous materials are superior for electrochemical performance due to the presence of more active sites and large specific surface areas. Among these, spinel cobaltites such as NiCo2O4, FeCo2O4, MnCo2O4, and ZnCo2O4, etc. have dragged considerable attention for supercapacitor electrodes due to the synergistic contribution of all the counterparts, which results in ameliorating specific capacitance with extended potential window, large electroactive sites, excellent electrical conductivity, and high electrochemical stability. newlineConsidering the above-mentioned facts, and the need for the fabrication of high-performance supercapacitors, the present thesis focuses on a three-step strategy - selection of suita