Reduced graphene oxide based ternary nanocomposite cathodes for high-performance aqueous asymmetric supercapacitors

Ternary nanocomposites have attracted increasing attention as efficient supercapacitor electrode materials. Here we report, the synthesis of a ternary hybrid nanocomposite by the introduction of crystalline RuO2 nanoparticles loaded carbon nanocoils (CNCs) as spacers in reduced graphene oxide (RGO). The RGO-(RuO2/CNCs) composite electrode exhibits a high specific capacitance of 725 F g−1 at a scan rate of 20 mV s−1 in three-electrode configuration. When used in symmetric two electrode configuration, it shows a specific capacitance of 436 F g−1 at a constant current density of 1 A g−1, which is nearly three times higher than that of pure RGO based electrode. An aqueous asymmetric supercapacitor fabricated using RGO-(RuO2/CNCs) as the positive electrode and RGO as the negative electrode is operational in an electrochemically stable potential window of 2 V. The asymmetric capacitor exhibits a high energy density of 45 Wh Kg−1 at a power density of 1 kW kg−1 and retains an energy density of 41 Wh Kg−1 even at a high power density of 40 kW kg−1.

Schematic and SEM image of RGO-(RuO2/CNCs) composite and schematic of the RGO-(RuO2/CNCs)//RGO asymmetric capacitor.191