Facile and fast synthesis of SnO2 quantum dots for high performance solid-state asymmetric supercapacitor

Herein, we demonstrate a facile microwave-assisted hydrothermal synthesis of SnO2 quantum dots as an active electrode material for supercapacitor applications. The SnO2 quantum dots were synthesized at 180 °C for 30 min by varying the ratio of ethanol and water (H2O) mixture. The as-synthesized SnO2 quantum dots were found to be tetragonal rutile structures with average particle size diameter 4–6 nm. The BET analysis with an optimized solvent ratio (10:30) was found to be highest surface area of 285.5 m2/g and shows pseudocapacitive behaviour with a specific capacitance of 315 F/g at a current density of 1 A/g in a three-electrode system. In addition, all solid state asymmetric supercapacitor (ASC) device was fabricated and it exhibits excellent energy density of 62 Wh/kg at power density 1 kW/kg.