MnO2/ordered mesoporous carbon nanocomposite for electrochemical supercapacitor

The preparation of composite manganese dioxide (MnO2) nanoparticles in an ordered mesoporous carbon (CMK-3) matrix and its use for constructing a new wide-potential-window supercapacitor is reported. CMK-3 is prepared using mesoporous silica as a hard template and sucrose as carbon source. The different ratios of MnO2/CMK-3 composite is synthesized by impregnating CMK-3 with a Mn(NO3)2·4H2O solution followed by annealing in nitrogen. Physical properties, morphology, and specific surface area were characterized by X-ray diffraction, transmission electron microscopy, and nitrogen sorption measurements, respectively. The electrochemical properties of the composite were studied by cyclic voltammetry, galvanostatic charge/discharge measurements, and impedance spectroscopy in aqueous solution. A symmetric supercapacitor based on the 40 % MnO2/CMK-3 composite electrode shows a high operation voltage of 2.0 V and specific capacitances of 640 and 440 F g−1 at discharge current densities of 1 and 10 A g−1, respectively. Almost no significant decrease in specific capacity is observed after 10,000 cycles at different charge/discharge rates.