Electrochemical capacitors based on the composite of graphene and nickel foam

Abstract

An improved Hummers method was developed for the simple and efficient production of high-quality graphene oxide (GO), and the composite of GO and nickel foam (NF) (GO/NF) was fabricated by ultrasonication-vacuum-assisted deposition of an aqueous solution of GO on NF. After chemical or thermal reduction, the composite of reduced GO and nickel foam (rGO/NF) was obtained. The electrochemical capacitance performance of rGO/NF was investigated using cyclic voltammetry and galvanostatic charge/discharge measurements. The chemically reduced rGO/NF composite (C-rGO/NF) exhibited high specific capacitance of 379 F/g at 1.0 A/g and 266.5 F/g at 10 A/g. We also prepared thermally reduced graphene oxide at 473 K in order to illuminate the difference in effect between the chemical and low-temperature thermal reduction methods on electrochemical properties. The cycling performance of thermally reduced rGO/NF composite (T-rGO/NF) and C-rGO/NF had ~91% and ~95% capacitance retention after 2000 cycles in a 6 mol/L KOH electrolyte, respectively. Electrochemical experiments indicated that the obtained rGO/NF has very good capacitive performance and could be used as a potential application of electrochemical capacitors. Our work revealed high electrochemical capacitor performance of rGO/NF composite and provided a facile method of rGO/NF preparation.