Partic. vol. 15 pp. 27-33 (August 2014)
doi: 10.1016/j.partic.2012.12.008

Microwave-hydrothermal preparation of a graphene/hierarchy structure MnO₂ composite for a supercapacitor

Zhong Chen^a, Jianling Li^a,*, Yu Chen^a, Yakun Zhang^a, Guofeng Xu^a, Jun Yang^b, Ye Feng^b

lijianling@ustb.edu.cn

Abstract

Graphene/hierarchy structure manganese dioxide (GN/MnO₂) composites were synthesized using a simple microwave-hydrothermal method. The properties of the prepared composites were analyzed using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. The electrochemical performances of the composites were analyzed using cyclic voltammetry, electrochemical impedance spectrometry (EIS), and chronopotentiometry. The results showed that GN/MnO₂ (10 wt% graphene) displayed a specific capacitance of 244 F/g at a current density of 100 mA/g. An excellent cyclic stability was obtained with a capacity retention of approximately 94.3% after 500 cycles in a 1 mol/L Li₂SO₄ solution. The improved electrochemical performance is attributed to the hierarchy structure of the manganese dioxide, which can enlarge the interface between the active materials and the electrolyte. The preparation route provides a new approach for hierarchy structure graphene composites; this work could be readily extended to the preparation of other graphene-based composites with different structures for use in energy storage devices.

Graphical abstract

Keywords

Graphene; MnO₂; Hierarchy structure; Supercapacitor