Design of Cube-like MnO2/r-GO Nanocomposite as a Superior Electrode Material for an Asymmetric Supercapacitor

Abstract

A pure MnO2 cube and MnO2 cube/r-GO nanocomposite were synthesized by the simple hydrothermal method. The structural formation, morphological and chemical composition of as-prepared MnO2 cube/r-GO nanocomposite were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The FE-SEM and TEM images were revealed that the MnO2 cubes are homogeneously distributed on the surface of r-GO nanosheets. The electrochemical results showed that the high specific capacitance of MnO2 cube/r-GO nanocomposite was 1570 F g−1 at a current density of 2 A g−1 in 1 M Na2SO4 electrolyte solution. The long life-term cycling performance of MnO2 cube/r-GO nanocomposite were delivered at outstanding capacitance retention of 99.3% subsequently 10,000 charge-discharge cycles at 8 A g−1. Moreover, we construct the asymmetric supercapacitor (ASC) of MnO2/r-GO//r-GO for practical application. Herein, MnO2/r-GO act as an anode material and r-GO as a cathode material. The assembled device shows a high specific capacitance of 92.49 F g−1 at 1 A g−1, high power density of 1.5860 W kg−1, and a high energy density of 17.7555 Wh kg−1 at 8 A g−1. Furthermore, the ASC device exhibits excellent capacitance retention of 98% after 10000 sequential charge-discharge cycles in 1 M Na2SO4 electrolyte solution. Based on the electrochemical performance as-prepared MnO2 cube/r-GO nanocomposite considered as the potential electrode material for energy storage application.