Effect of Hydrothermal Temperature on the Structure and Electrochemical Performance of Manganese Compound/Ordered Mesoporous Carbon Composites for Supercapacitors

Abstract

Manganese compound/ordered mesoporous carbon (OMC) composites with host-guest structure were prepared by a novel technique named as incipient wetness impregnation-hydrothermal method, which combines incipient wetness impregnation and hydrothermal method, and the effect of hydrothermal temperature on the structure and electrochemical performance of the composites was investigated. The structure of the composites was characterized by X-ray diffraction (XRD), adsorption/desorption isotherms and transmission electron microscopy (TEM), and electrochemical performances was tested by cyclic voltammetry. XRD shows that MnO2/OMC composites was formed at lower temperature of 120 and 150°C, and MnOOH/OMC composite at higher temperature of 175°C. Adsorption/desorption isotherms and TEM studies confirm the formation of host-guest structure for manganese compounds/ordered mesoporous carbon composites. The optimum hydrothermal temperature is confirmed to be 120°C, and the composite prepared at this temperature exhibits 482.59 F/g of specific capacitance in 1 M LiOH electrolyte at the scan rate of 5 mV/s, which is twice of that of OMC. The MnO2/OMC composite prepared at 120°C shows an excellent long-term recycling capability.