Chemically Reduced Graphene Oxide for Supercapacitor Applications

Abstract

Recent demands on energy storage opened up many challenges and opportunities in the domain of electrochemical devices such as batteries and supercapacitors. Supercapacitors are known for high power supply in short time, long life cycle and eco-friendly operation. Owing to its remarkable properties, graphene (single layer of graphite) – an allotrope of elemental Carbon and a 2D material discovered in 2004 – has emerged as a promising active-electrode material for developing high-performance supercapacitors. However, obtaining single layers of graphene in large scale by bottom-up approach is extremely difficult. Thus, a top-down approach whereby graphite is first chemically oxidized to graphene oxide (GO) and subsequently reduced to reduced graphene oxide (rGO) which exhibits physicochemical properties in close resemblance to pristine graphene has emerged. This thesis aimed at exploring unconventional transition metal salts-based reducing agents in the chemical reduction of GO to rGO and to use rGO as such (without further treatments) in the fabrication of all solid-state supercapacitors. The overall electrochemical performance of our rGO was found to be much superior in comparison to rGO obtained by conventional reducing agents such as NaBH4, and N2H4. To further boost the capacitance values of rGO supercapacitor, successful usage of organic electrolytes, metal-ion additives, optimal concentration of gel polymer electrolyte and blending with conducting polymer (namely polyaniline) were demonstrated. Finally, our process of producing rGO by top-down chemical approach in large scale was realized to be highly economic and thereby promising for supercapacitor applications at industrial level.