Graphene aerogel for supercapacitors: influence of hydrothermal reduction parameters on electrochemical performance

In the present work, a hydrothermal reduction method is used to further enhance and optimize the pristine graphene aerogels (GAs) for supercapacitors. Three key variables (GO concentration, hydrothermal reduction temperature, and time) were optimized through the application of Taguchi design of experiments to the synthesis process. A total of nine experimental runs were conducted and repeated three times to confirm reproducibility. Electrochemical performances of the electrodes were evaluated by cyclic voltammetry (CV), galvanostatic discharge-charge (GCD), and electrochemical impedance spectroscopy (EIS). The optimized sample (5 mg/mL GO at 180 °C for 16 h) was further analyzed using morphological studies, including FIB-FESEM, Raman, XPS, and BET. The as-obtained 3D reduced graphene oxide network exhibited a maximum specific capacitance of 182.33 F/g at the current density of 0.2 A/g, corresponding to an energy density of 6.33 Wh/kg at a power density of 108.5 W/kg in a 6 M KOH electrolyte. This study systematically investigates the influence of hydrothermal reduction parameters on the energy density of graphene aerogel-based supercapacitors and pinpoints the best synthesis conditions. This also highlights the potential of pure GA as an electrode material, indicating opportunities for further enhancement through ongoing research and development.