Promotion On The Capacitive Performance Of Thermal Reduced Graphene Oxide/Manganese Dioxide Composites

Supercapacitor, as a kind of new energy storage device, with high power density, long cycle life, wide working temperature range and environmental friendly, have broad application prospects in electronics, machinery, new energy vehicles and so on various aspects, so has become a hot research topic in the field of energy storage. The key elements affecting the performance is electrode materials used for the preparation of super capacitor, therefore the preparation of electrode materials become a key point in the study of super capacitor.In this paper, carbon materials and manganese dioxide were chosen as electrode materials, because of low cost and good environmental compatibility.MnO2was prepared by liquid phase method; graphite oxide was prepared by modified Hummers method, and ultrasonic dissection for graphene oxide, and then the thermal reduction; Both was composited for electrode materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier infrared (FTIR), four probe method, and cyclic voltammograms tests were applied to characterize and analyze the surface morphology, microstructure of the composite, the conductivity and specific capacitance. After thermal reduction, lamella spacing of graphene oxide decreased, and the structural integrity was damaged to some extent, fragmental,which increased the specific surface area. In addition, thermal reduction of different temperature made the oxygen-containing functional groups from the graphene oxide removed inordinately, and its conductivity also increases with the increase of thermal reduction temperature at the same time. On the cyclic voltammograms test, under the scanning rate of2mV/s, specific capacitance value of graphene oxide without thermal reduction is5F/g, which was obtained by calculation. Its specific capacitance values increased firstly and then decreased with the temperature of heat reduction increased, of which when the temperature of heat treatment was600℃, the specific capacitance was the highest,42F/g.Manganese dioxide prepared by reduction of potassium permanganate using ethanol was determined to8-MnO2by test, which owns good electrochemical properties, and its microstructure is stratified structure. Its specific capacitance value was171F/g, which was obtained by cyclic voltammograms test calculation under the scanning rate of2mV/s.Compared with pure MnO2and without thermal reduction of GO/MnO2electrode materials, the specific capacitance of the electrode materials composited MnO2and GO on thermal reduction were improved. It could have the following reasons. GO join significantly reduced the degree of agglomeration of MnO2, and increases the MnO2participation constraint capacitance reaction of the active area. And thermal reduction of GO can effectively improve the electrical conductivity of the composite, its residual oxygen containing functional groups provided the certain constraint capacitance, thus the composite condenser performance is improved.