Design of nickel oxide nanoclusters on nano-graphitized coil sheets derived from Sapindus mukorossi for high-performance supercapacitor applications

The carbon materials have been widely used as electrode materials for supercapacitor applications (SC) for improving electrochemical performance. The preparation of working electrode can be done using carbon material due to their economic, environmental, and sustainable characteristics. The nickel oxide nanoclusters on nano-graphitized coil sheets (NNNGCS) based on Sapindus mukorossi extraction through graphitization and annealed at 450 degrees C using hydrothermal method. The NNNGCS and NiO are analyzed by various analytical techniques. The nickel oxide nanoclusters formed on nano-graphitized coil sheets (NNNGCS) are observed from FESEM analysis. Electrochemical studies have been carried out in three electrode systems at 1 M KOH aqueous solution. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) are utilized to investigate the electrochemical performance. The specific capacitance values of NNNGCS and NiO are 658 F g(-1) and 363 F g(-1) and specific capacity values of NNNGCS and NiO are 263 Cg(-1) and 145 Cg(-1) respectively. The GCD curves of NNNGCS show cycling stability over 5000 cycles and showed an excellent performance, where its coulombic efficiency (eta %) is 98.8% at 10 A g(-1)and capacity retention 88%. The constructed ASCs device delivered a maximum energy density of 27 Wh/kg at a power density of 4200 W/kg.