Hydrothermal synthesis of MnO₂@graphene/activated carbon composite electrode with enhanced electrochemical performance for supercapacitor applications

Abstract

We report the preparation of an electrode material made up of MnO 2 /graphene/ activated carbon ternary composite by hydrothermal method for supercapacitor (SC) applications. The prepared ternary composite has been characterized by using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman spectroscopy measurements. The prepared objective electrode has been investigated using galvanostatic charge-discharge (GCD) and cyclic voltammetry (CV) measurements in a 3-electrode system using 3M KOH aqueous electrolyte for the analysis of their electrochemical performance. The prepared MnO 2 /graphene/activated carbon composite results in maximum capacitance of ∼493.57 F/g at 5 mV/s using CV and moreover the highest capacitance obtained from the GCD measurement is ∼485.29 F/g at 1 A/g. The long-term cycle stability of the composite electrode is also demonstrated and it shows outstanding cyclic performance where 97% of capacitance is left over 5000 cycles at 1 A/g. Therefore, the composite shows good charge storage performance, as well as tremendous cycle stability and that, reveal the synthesized ternary composite can be a suitable electrode for SC applications.