Fabrication of an asymmetric supercapacitor based on reduced graphene oxide/polyindole/γ - Al2O3 ternary nanocomposite with high-performance capacitive behavior

This report describes the design and fabrication of reduced graphene oxide/polyindole/gamma-Al2O3 (RGO/PIn/gamma-Al2O3) ternary nanocomposite electrode materials for asymmetric supercapacitors. The nanocomposite was prepared by chronoamperometry on a gold electrode. Polyindole (PIn) and RGO/PIn were prepared electro-chemically and their performances were compared with RGO/PIn/gamma-Al2O3. The structures and morphologies of samples were characterized by FESEM, EDX, XRD and FT-IR. To get electrochemical charasteristics of the RGO/PIn/gamma-Al2O3 electrode in a HClO4 solution electrolyte Cyclic voltammetry (CV) technique, electrochemical impedance spectroscopy (EIS) and galvanostatic charging and discharging were carried out. The results show that RGO/PIn/gamma-Al2O3 performed well with a specific capacitance of 308 F/g in comparison with PIn (93 F/g) and RGO/PIn (214 F/g). RGO as the negative and RGO/PIn/gamma-Al2O3 as the positive electrode were used to fabricate an asymmetric supercapacitor. The asymmetric RGO/1.0 M HClO4 /RGO/PIn/gamma-Al2O3 supercapacitor can be cycled in a high voltage range of 0.0-1.4 V that displayed a high energy density of 10 Wh/kg at a 3880 W/ kg power density and a specific capacitance of 38.46 F/g. Furthermore, after 5000 cycles, 83% of the RGO/PIn/gamma-Al2O3 initial capacitance was maintained.