Reduced graphite oxide-pure water supercapacitor: A futuristic water based energy storage device

Abstract With the ever-increasing use of supercapcitors, there is a need for exploring more environment friendly active material-electrolyte combinations. Herein, we report an environmentally benign supercapacitor employing reduced graphite oxide obtained by hydrazine reduction of graphite oxide as active material and pure water (HPLC grade) as ‘electrolyte’. We could achieve a specific capacitance of 333 Fg-1 at a galvanostatic charge-discharge current of 0.3 Ag-1. Maximum energy and power density values are 29.6 Whrkg−1 and 266.2 Wkg-1 respectively. Energy storage mechanism is the diffusion of hydronium ions within the interlayer region of the active material. Hydronium ions are produced by the hydrolysis of hydroxyl groups at the active material - water interface. This supercapacitor exhibits good cycle stability. Concentration of hydroxyl groups is found to be crucial in determining the electrochemical performance. This supercapacitor is thermally self-chargeable with a thermoelectric coefficient of 4.07 mV°C−1 which makes it even more futuristic and environment friendly.