Electrochemical Capacitance Performance Of Nickel Hydroxide And Its Composites Electrodes

Supercapacitors as a new type of energy storage devices have the advantages of highpower density, high charge-discharge efficiency, long cycle life and high environmentalacceptability,but supercapacitors has lower energy density compared to secondary battery. Somany researchers of the supercapacitor have focused on developing a comprehensiveperformance and low cost of the materials. In a variety of the material, nickel, cobalt etltransitional metal oxides and hydroxides with abundant resources and low cost, excellentperformance and the advantages become the hotspot of the supercapacitor. This thesis consistsof four parts.The purpose of the first chapter is to survey the energy storage mechanisms, categories,characters, applications of electrochemical capacitors, and the study of microwave-assistedhydrothermal methods, particularly the progress of electrochemical capacitors using carbon,metal oxide, hydroxides, conducting polymer as electrode materials and so on. According toall the above information, I put my views, purposes and researches in this field.The second chapter shows the nano-sized flower-likeα-Ni(OH)₂ as electrode materialsprepared by microwave-assisted hydrothermal methods. All tests indicate that the variousreactants ratio had an effect on the morphologies and the electrochemical capacitanceperformance of the electrode materials.The third chapter, divided into two parts, investigates the preparation and theelectrochemical capacitance performance of Ni-Co double hydroxides:1. Ni-Co double hydroxides were fabricated by microwave-assisted hydrothermalmethods, using CTAB,Tween-80 as the surfactant. Comparing with the sample withoutadding surfactant, the results exhibit there being much difference of the morphologies andelectrochemical performance among the three materials. Moreover, Ni-Co double hydroxidesfabricated using Tween-80 as the surfactant has excellent electrochemical performance withthe initial discharge capacity of 1437 F·g^-1.2. Ni-Co double hydroxides with different molar ratios of Ni/Co were fabricated bymicrowave-assisted hydrothermal methods using Tween-80 as the surfactant. The results show the morphologies and the electrochemical capacitance performance of the materialshave much difference about Ni-Co double hydroxides with different molar ratios.The forth chapter investigates the preparation and the electrochemical capacitanceperformance of Ni-Co-Al three hydroxides, mainly divided into three parts:1. Ni-Co-Al three hydroxides were prepared by microwave-assisted hydrothermalmethods, still using CTAB,Tween-80 as the surfactant. Comparing with the sample withoutsurfactant, the results exhibit there being much difference of electrochemical performanceamong the three materials. Ni-Co-Al three hydroxides fabricated using CTAB as thesurfactant has the best electrochemical performance with the initial discharge capacity of1482 F·g^-1, and the sample synthesized by Tween-80 as the surfactant showed the better cyclestability.2. Ni-Co-Al three hydroxides with different molar ratios of (Ni+Co)/Al were fabricated bymicrowave-assisted hydrothermal methods using CTAB as the surfactant. The results showthe morphologies of the materials have a close relationship about (Ni+Co)/Al threehydroxides with different molar ratios, but the electrochemical performance has greatdifference.3. (Ni+Co)/Al three hydroxides with different molar ratios of (Ni+Co)/Al weresynthesized via microwave-assisted hydrothermal methods with Tween-80 as the surfactant.The results exhibit much difference of electrochemical performance of (Ni+Co)/Al threehydroxides with different molar ratios. And when the molar ratio of (Ni+Co)/Al is 7:3, thematerial exhibits excellent cycling stability.