Preparation of graphene/nano-MnO2 composite and its electrochemical performance as supercapacitor electrodes

The graphene/nano-MnO₂ composite was synthesized by a chemical co-precipitation method. The crystal structure and the surface topography of all materials were characterized by means of X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectrum and scanning electron microscopy(SEM). The results of XRD pattern and FTIR spectrum reveal that a high quality graphene has been synthetized successfully. The SEM images show that nano-MnO₂ has a honeycomb structure formed by nanoplatelets and nano-MnO₂ spheres are dispersed on the surface of graphene layer in graphene/nano-MnO₂ composite. The electrochemical properties of the composite were evaluated by cyclic voltammetry and galvanostatic charge/ discharge respectively. The graphene/nano-MnO₂ hybrid material was used for investigation of electrochemical capacitive behaviors. The results of cyclic voltammetry test show that the composite have good eletrochemical performance and the average capacitance is as high as 159F/g in the 6 M KOH aqueous electrolyte.