The Preparation And Electrochemical Performance Of Nanoarray Composite Electrode Materials

As one of the new energy components, supercapacitor has drawn more and more attention with its large power density, long cycle life and fast charge and discharge. The electrode material is the main factor which decided the electrochemical properties of the supercapacitor. Due to the reversible electrochemical reaction, the transition metal oxide electrode materials have the better capacitive performance than the carbon materials. Specially, such a highly ordered nanoarray architecture can offer a larger specific surface area, excellent electrical conductivity and high speed ion/electron transport channel. Besides, the nanoarray architecture materials can directly use as the supercapacitor electrode without extra conductive or binder materials, and can effectively improve the utilization of active material. Moreover, the hierarchical nanoarrays can efficiently utilize the synergistic effect between the different materials, leading to a superior electrochemical performance. The main object in this research is to synthesise different one-dimensional nanoarray composites for improving the electrochemical performance of the supercapacitor. And the main contents are as followed:1、First, we use the electrochemical anodization to synthesize TiO₂ nanotube, then deposited MnO₂ nanoparticles by using the hydrothermal process. Moreover, after the TiO₂ nanotube annealing in following hydrogen, H-TiO₂/MnO₂ nanocomposite has the better electronic conductivity. In order to further enhance the electronic conductivity, using the hydrothermal process to deposited carbon and the H-TiO₂/C nanocomposite has the superior conductivity. Meanwhile the TiO₂ nanotube can provide a large surface area for the deposition of MnO₂, enabling high utilization of MnO₂. Due to the unique structure, the hydrogenation and carbon-coated process, the H–TiO₂/C/Mn O2 electrode exhibited a high speci?c capacitance of 66.2 mF cm-2（299.8 F g-1） at the current density of 0.5 A g-1with an excellent cycling stability.2 、 NiCo₂O₄ nanowire arrays were first synthesize by the hydrothermal process, and then served as the backbone to deposite the MnO₂ nanosheet and Ni O nanosheet. With the large specific surface area and good electrical conductivity, NiCo₂O₄ nanowire arrays show the excellent electrochemical performance. But, due to the poor electrical conductivity and the compact structure of the MnO₂, NiCo₂O₄ nanowire didn’t show its electrochemical performance. The specific capacitance of the NiCo₂O₄@MnO₂ is decreased compared with the pureNiCo₂O₄ nanowire array. NiCo₂O₄@NiO nanocomposite has the superior electrochemical performance than the NiCo₂O₄ and NiCo₂O₄@MnO₂, with a high speci?c capacitance of 1453.26 F g-1 at the current density of 1 A g-1. However, the structure of the NiCo₂O₄@Ni O nanocomposite has changed in the cycling process, leading to poor cycling stability. Chose shell material with the good conductivity and loose structure will increase the specific capacitance of the nanocomposite. And the structure of the nanocomposite should stable to improve the cycling stability.