Supercapacitors Preparation And Properties Of The Ruthenium Oxide-based Composite Thin Film Electrode

Centering on the research and development of low-cost and high specific capacitance electrode materials used in supercapacitors, the methods of electro-deposition preparing (RuO2/MnO2)·nH2O composite electrode films, coating and thermal decomposition preparing (RuO2/Co3O4)·nH2O composite electrode films and colloid preparing (RuO2/AC)·nH2O composite electrode were investigated in the dissertation. We optimized the preparation technology parameters of the three methods of composite electrode films and mainly studyed the effects of different doping systems, composition and heat treatment on the overall performance of the three kinds of composite films. Scanning electron microscopy, X-ray diffraction, infrared spectroscopy and electrochemical workstation was used to deeply research the morphology, phase structure, physical and electrochemical properties of the three kinds of composite films.The main research contents are as follows:(1) We have choosed electro-deposition method to prepare the (RuO2/MnO2)·nH2O composite film.It can get excellent adhesion force and specific capacitance when the molar concentration ratio of MnⅦ:Ru3+ is 3:1 in initial electrodeposition solution at 250℃for 2.5 h of the heat treatment process,which separately are 14.8 MPa and 418F/g.Its CV curves show that the (RuO2/MnO2)·nH2O composite films express typical capacitance characteristic at different scanning rate, and the charging and discharging curve are symmetrical with low voltage drop relatively.Its specific capacitance maintains at 94.73% after 1000 charge-discharge cycles,which confirm the trust of low resistance and stable electrochemical properties of the composite films.(2) The (RuO2/Co3O4)·nH2O composite films electrode have been prepared by in-situ thermal decomposition using precursor of isopropanol solution of RuCl3·3H2O and Co(CH3COO)2. When the molar concentration ratio of Ru3+:Co2+ is 1:3, the composite films got the best performances after 3 hours at 260℃,which the specific capacitance of the film is 569F/g, adhesion force is 22.4MPa and specific surface area is 336.5m/g. It shows that the (RuO2/Co3O4)·nH2O composite films have excellent electrochemical properties after the charge/discharge and AC impedance test.The internal resistance of the composite films only is 0.42Ωand its specific capacitance maintains at 97.65% after 1000 charge-discharge cycles.(3) Using colloidal method to prepare the (RuO2/AC)·nH2O composite electrode containing 40wt% active carbon, it remains the characteristics of the high specific capacitance of ruthenium oxide and high specific surface area of active carbon. The composite electrode can get stable performances which the specific capacitance is 445F/g, intenal resistance 0.68Ω, specific surface area 307m2/g and adhesion force 10.5MPa at 240℃for 4h. The constant current charge-discharge test show that the composite electrode has the typical characteristics of the capacitor with the time of discharge to 550s. The capacitance of (RuO2/AC)·nH2O composite electrode remain at 93.1% after 1000 charge-discharge cycles.