Manganese dioxide-coated activated mesocarbon microbeads for supercapacitors in organic electrolyte

MnO2 nanostructures are successfully coated onto activated mesocarbon microbeads (a-MCMB) by a simple chemical coprecipitation method. The structure and morphology of the as-prepared a-MCMB/MnO2 composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the nano-MnO2 is of short fiber-like structures with about 200 nm in length and 60 nm in width. A growing mechanism was also proposed for the nano-MnO2 on the surface of a-MCMB. This novel composite was used as an electrode material for supercapacitors. Electrochemical measurements showed that the composite electrode has a maximum specific capacitance of 183 F g−1 in 1 M LiPF6 (EC + DMC) organic electrolyte with an operating voltage up to 3.0 V. The specific capacitance base on the MnO2 is estimated to be as high as 475 F g−1, corresponding to a considerable energy density of 106 wh kg−1.