Synthesis, Modification And Electrochemical Performance Of Titania Nanostructures

In order to meet the application requirements, lithium-ion secondary battery should have superior cycling stability, high power density and energy density. As an anode material, it was demanded that during the cycling course, lithium-ion should have shorter transfer route in the electrode and the volume change of the anode material should be as small as possible during the lithium ion insertion and extraction processes. The anode material with nanosized and peculiar structure was considered as an appropriate candidate.In this paper, different kinds of nanostructural titanium oxides including nanoparticles and nanotubes were prepared via the solvothermal method. Ag and carbon nanotubes modified TiO₂ nanoparticles and TiO₂-SnO₂ nano-solid solution were also prepared. The electrochemical properties of these materials as anode materials for lithium-ion batteries were investigated.The results show that the TiO₂ nanoparticle electrode holds a lower reversible capacity and a smaller irreversible capacity loss than the TiO₂ nanotubes electrode. Alternative current impedance spectroscopy result shows that the transfer rate of Li-ion in TiO₂ nanoparticle electrode is higher than that in TiO₂-NTs electrode. During the annealing course at 300 and 500℃, the structure of lepidocrocite TiO₂ nanotube was collapsed, and was gradually transformed into anatase nanoparticles. The electrochemical measurements showed that all electrodes exhibit a perfect cycling performance, and the TiO₂-NTs annealed at 500℃exhibits the highest first coulombic efficiency of 41.2% and higher (the transfer of) Li-ion transfer rate.Ag-TiO₂/CNTs composites were prepared via hydrolysis and reduction processes. The electrochemical measurements showed that the Ag-TiO₂/CNTs electrode presented a higher reversible capacity of 172mAh/g after 30 cycles, superior cycle performance and favorable electrochemical kinetics compared with the other electrodes. The Ag addition not only increases the electronic conductivity of composites, but also facilitates transfer of the Li ion in the composite electrode.According to the design route for acquiring better cycling performance and high reversible capacities of lithium-ion batteries anode materials, amorphous TiO₂-SnO₂ nano-solid solution were prepared via solvothermal method by using water and ethanol as solvent. The results show that the lithium storage mechanism of TiO₂-SnO₂ nano-solid solution is different from that of the TiO₂ and SnO₂, the first reversible capacity of the nano-solid solution electrode is 653mAh/g, and the reversible capacity holds about 490mAh/g after 30 cycles, which was only 0.83% loss of coulombic efficiency for each cycle. Alternative current impedance spectroscopy result shows that the transfer rate of Li-ion in TiO₂-SnO₂ nano-solid solution is higher than that in TiO₂ and SnO₂ nanoparticle. The nano-solid solution electrode possesses not only the better cycling performance of TiO₂ material, but also the high reversible capacity of SnO₂ electrode, which will become a promising anode material for the next generation of lithium ion batteries.