Preparation And Electrochemical Property Of Ruthenium Oxide Composite Electrode Materials

Supercapacitor is a new-style electrochemical device with high energy storage. Theelectrode material is vital to the supercapacitor with excellent performance, and it containscarbon, transition-metal oxide and conducting polymer. Among them, the Faraday capacitor oftransition-metal oxide RuO2electrode material attracts great attention due to its high specificcapacity, low resistivity and other excellent properties. But the defect of separate material limitstheir application. Therefore, research on composite for ruthenium oxide with carbon materials,other transition metal oxide, conducting polymer and others is more and more significant, andthe electrochemical performance of the material will be improved with the development ofsupercapacitor.In this paper, two kinds of ruthenium oxide based composite were prepared by alkoxidehydrolysis. One is the RuO2/nano-C composites prepared by ruthenium oxide and nano graphitewith small size in the ethanol ruthenium hydrolysis. Another is the RuO2/SiC-NWs compositesprepared by ruthenium oxide and silicon carbide nanowires in the ethanol ruthenium hydrolysis.Silicon carbide nanowires have some characteristics of high dielectric constant, high thermalconductivity and saturated electron drift velocity. On the basis, further study of preparation,morphology and electrochemical properties of the two kinds of composite was conducted. Themain conclusions are as follows:(1) Nano graphite was prepared by carbonization method of phenolic resin in hightemperature. The analysis of XRD and SAED show that the nano graphite consisted ofcrystalline state and non crystalline state. And the TEM analysis shows that the diameter ofnano graphite particle was20~50nm, and the shape was spheroidal, and the distribution isuniform.(2) Through the method of sol-gel and carbothermic, the silicon carbide nanowire wasprepared by using TEOS and activated charcoal as the source of silicon and carbon. Theanalysis of XRD and SEM indicate that the silicon carbide nanowires were mainly moniliformsilicon carbide nanowires, also contained cylindrical silicon carbide nanowires. The length ofmoniliform silicon carbide nanowires was150μm. It consisted of two segments, the middlewas beta silicon carbide nanowire crystalline with about20nm diameter, and moniliform beadscoated on the surface with about100nm diameter. (3) The SEM and TEM of RuO2/nano-C and RuO2/SiC-NWs composites display thatruthenium oxide deposited on the surface of nano graphite and silicon carbide nanowires in thehydrolysis process of ethanol ruthenium. With the increasing of ruthenium content in thecomposite, the amount of ruthenium oxide on the surface of nano graphite and silicon carbidenanowires increased gradually. A large number of ruthenium oxide uniformly deposited on thesurface of nano graphite and silicon carbide nanowires when the ruthenium content in thecomposite was12.0wt.%. The analysis of FTIR shows that Si-Ru bond was formed byinteraction, so as to improve the stability of RuO2/SiC-NWs composite.(4) The current large absolute value range in the cyclic voltammetry curve of RuO2/nano-Cand RuO2/SiC-NWs composites indicated a good capacitor performance. With the increase ofruthenium content, the area of cyclic voltammetry curve, namely, the electric capacity increased.While the ruthenium content was12.0wt.%, the specific capacitance of RuO2/nano-C andRuO2/SiC-NWs composites reached314F·g-1and393F·g-1respectively. Electrochemicalimpedance spectroscopy showed that RuO2/nano-C and RuO2/SiC-NWs composites consistedof electric double layer capacitance behavior and faradaic pseudo capacitance behavior. Thetwo composites had excellent impedance characteristic, the equivalent series resistancedecrease with the increase of ruthenium content in the two composites. The capacitance losswere0.81%and0.76%respectively after1000charge discharge cycles, when rutheniumcontent of RuO2/nano-C and RuO2/SiC-NWs composites was12.0wt.%.