Double layer capacitor based on active carbon and its improved capacitive properties using redox additive electrolyte of anthraquinonedisulphonate

Anthraquinone-2,7-disulphonate (AQDS) added into neutral electrolyte of KNO3 in symmetric active carbon (AC) capacitor was assessed by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. The Faradaic redox reactions were diffusion-controlled and the working window could be extended to 1.8 V. During the charging and discharging processes, the redox reactions occurred on the cathode, leading to considerable enhancement of specific capacitance, power density and energy density, which were 225 F/g, 412 W/kg and 21.2 Wh/kg, respectively at a current density of 1.0 A/g for a symmetric AC capacitor in the electrolyte of 1.0 M KNO3 with 0.1 M AQDS.