Preparation And Electrochemical Investigate On Ru-based Metal Oxide Composites

In recent years, the researches on electrode material of supercapacitors have been paid much attention by many countries. The key factor is how to increase the power and energy density. My studies mainly focus on the preparation of Ru-based composite electrode materials with low cost, good electrochemical capacitance behavior and long cycle life. The details are as follows:1. Co₃O₄/RuO₂·xH₂O composites with various molar ratio of Co:Ru were synthesized by one-step co-precipitation method which showed high water content, mesoporous structure, and high specific surface area. The composite annealed at 200°C exhibited a high specific surface area of 107 m2·g-1. The electrochemical performance of these composites was measured in 1 M KOH electrolyte. The specific capacitance of the composites increased significantly with the increasing of the molar content of Ru. We also observed that the annealing temperature had a great role on the electrochemical activities and cycle stabilities of the composite, the capacitance decreased and the cycle stabilities were enhanced at a high heat treatment temperature. Meanwhile, the composite annealed at 200°C showed a capacitance of 465 F/g with good cycle stability.2. In order to improve the low power density of metal oxides, we prepared Co_0.5Ru_0.5O_1.67·xH₂O/MWNTs composites. The results revealed that the capacitance of single eletrode was as high as 452 F/g and the capacitance of Co_0.5Ru_0.5O_1.67·xH₂O was 820 F/g. The symmetric surpercapacitor based on Co_0.5Ru_0.5O_1.67·xH₂O/MWNTs was also prepared which showed a capacitance of 91 F/g. Meanwhile, a power density as high as 1562 W/kg and an energy density of 11.3 Wh/kg were obtained.3. Asymmetric supercapaciotors based on Co₃O₄/RuO₂·xH₂O composite and Co_0.5Ru_0.5O_1.67·xH₂O/MWNTs as positive electrodes and activated carbon as negative electrode were successfully fabricated. The results showed that the Co₃O₄/RuO₂·xH₂O composite and activated carbon asymmetric supercapacitor delivered an energy density of 25 Wh/kg and a power density of 127 W/kg in a potential window range from 0 to 1.4 V, and a power density of 342 W/kg was obtained with an energy densiy of 10.1 Wh/kg for Co_0.5Ru_0.5O_1.67·xH₂O/MWNTs and actived carbon asymmetric supercapacitor.4. Well-ordered mesoporous carbon-silica composites had been successfully prepared by using linear oligomers as carbon precursors, silica as building blocks and Pluronic surfactant F127 as template through one-step self-assemble method. Based on the as-prepared carbon-silica nanocomposites, MC-Si/RuO₂·xH₂O composite fabricated by sol-gel method was also investigated. A capacitance of 262 F/g was obtained for the MC-Si/RuO₂·xH₂O composite (20 wt.% RuO2, 1035 F/g based on RuO2), which is recognized as one promising material in the application of supercapacitors.