Study On Preparation And Supercapacitance Of NiO And RuO₂ Electrode Materials

Supercapacitor is a new kind of energy storage device.Electrode material is the basis to guarantee supercapacitor with excellent supercapacitive properties. This dissertation mainly investigated preparation and supercapacitive performance of RuO₂·xH₂O film electrode, nano NiO electrode and their composite electrode materials. Good results have been gained in this dissertation.Cathodic electrochemical deposition method was introduced to prepare RuO₂·xH₂O film on Ti electrode. Its surface structure, electrochemical performance and influence of specific capacitance on deposited weight of RuO₂·xH₂O were studied, furthermore to find the best deposited weight. The result indicated that the specific capacitance of RuO₂·xH₂O reaches 786 F/g, with the discharge-charge efficiency of 99.6%.The RuO₂·xH₂O electrode shows good power characteristic and an excellent cycle performance.RuO₂ was deposited on CNTs to get RuO₂·xH₂O/CNTs composites by ultrasonic synthesis process. RuO₂ were modified with CNTs, and the specific capacitance of RuO₂·xH₂O reaches 865 F/g. The RuO₂·xH₂O/CNTs nano composite powder was prepared by cathodic deposition method. In 1.0 mol/L H₂SO₄ solution, the specific capacitances of CNTs and RuO₂·xH₂O/CNTs nano composite were 18 and 159 F/g, respectively. The results display that CNTs was composed to enhance the utilization of RuO₂ and improve the power characteristics of RuO₂.Nano NiO electrode material with various morphologies was prepared by the methods of chemical precipitation, molten salt synthesis and hydrothermal synthesis, respectively. Pseudocapacitance behavior of the as prepared NiO electrode was studied in 2.0 mol/L KOH solution. The result exhibited that NiO electrodes showed excellent pseudocapacitance characteristics in 2.0 mol/L KOH solution and their highest specific capacitances are 92, 65.4 and 137 F/g.Rare earth elements doped nano-NiO electrodes were fabricated by chemical co-deposition reaction. Influence of NiO electrochemical capacitive performance on different rare earth elements were investigated to Find the best rare earth element doped. The results indicated that when ratio of n(Dy) to n(NiO) is 2:98, The specific capacitance of the Dy doped NiO electrode reaches 147 F/g.Porous nickel oxide/ carbon nanotubes (NiO/CNTs) composite precursor was synthesized using sodium dodecyl phenyl sulfate as a soft template and urea as hydrolysis-controlling agent. After heat treatment, NiO with a high specific surface area of 228 m²/g was obtained. The charge/discharge capability of the NiO/CNTs composite at a high specific current density were studied for the first time in 2.0 mol/L KOH electrolyte. The composite has a specific capacitance of 191 F/g and shows an excellent cycle performance at a high current density of 2 A/g. A specific capacitance approximate to 206 F/g has achieved with NiO/CNTs (10 wt.%).Supercapcitors are fabricated using pure NiO and NiO/CNTs composite as electrode material, and their capacitances for supercapcitors are 4.4 and 6.4 F,respectively.