Preparation And Properties Of Supercapacitors Ruthenium Dioxide/Graphene Composites

As a new type of energy storage device, supercapacitors have many advantages, such as high discharge specific power, excellent transient charge and discharge performance and extremely long cycle life。With the development of modern industry, the applications of small and non-polluting supplies become more widely. Supercapacitors electrode material affect its performance, we must first prepare electrode materials for high energy density, high power density, large specific capacity, in order to improve its performance. Current electrode materials used in the commercialization of supercapacitors mainly include activated carbon material which based on double layer energy storage mechanism, and metal oxide material which based on Faraday energy storage mechanism。metal oxides have been a hot topic in research field because of their higher energy density and long cycle life.RuO2has a distinct advantage in the metal oxides, its capacity and cycle life characteristics are better than other metal oxides. Unfortunately, the high price restricted the industrial application and promotion.Graphene material with unique physical and chemical properties caused extensive concern of scientists. Use the graphene as double-layer capacitor electrode materiel,its unique layered structure is conducive to the rapid diffusion of the electrolyte in its internal,realize the electronic components instantaneous time high-power charge and discharge. This dissertation is carried out following the international foreland research. Graphene was prepared by oxidation and reduction process,amorphous ruthenium oxide materials was prepared by sol-gel process and prepared the RuO2/grapheme nanocomposites through the co-precipitation. We studied its electrochemical properties in the supercapacitors and draw the following conclusions:1. We used titanium as the collector and graphene as the electrode materials for supercapacitor. Electrochemical performance tests show that in1mol·L-1H2SO4electrolyte, electrode material has a significant double-layer capacitance characteristics of graphene, graphene capacitors has a good cycle stability and power characteristics in0～1V operating voltage.2. Amorphous ruthenium oxide material was prepared by sol-gel method. Ruthenium oxide materials have a smaller particle size less than50nm through the SEM and TEM.There are some agglomeration between the particles. The electrochemical tests indicated that the ruthenium oxide materials exhibit a high specific capacitance a first discharge capacity of802F/g at the current density of1A/g. And have a good cycle life the capacity after3000cycles still416F/g.3. The RuO2/grapheme nanocomposites materials were prepared by co-precipitation method. The reunion between the ruthenium oxide particles decreased in nanocomposites materials,and the composites of ruthenium oxide electrochemical performance is greatly improved, recycling life and charge-discharge stability compared to pure ruthenium oxide materials is much better, pure ruthenium oxide material after2000cycles of charging and discharging capacity of a sharp decline.when the graphene content of5%, the composites showed excellent electrochemical performance, the first discharge capacity is740F/g at the current density of2A/g, after a depth of8000charge-discharge cycles, the capacity can still maintain71%.4.Hybrid capacitor was assembled with ruthenium oxide as cathode and graphene as anode. When the mass ratio of ruthenium oxide and graphene was1:4, the hybrid capacitor had the best capacity of50.7F/g. At1A/g current density, the capacitor delivered a specific energy and specific power of14.1Wh/kg and233.3W/kg, respectively. It had excellent cycle stability as well, the capacity retention of which was99%after2000charge-discharge cycles.