Preparation And Modification Of TiO₂-B Anode Materials For Advanced Li-ion Battery

In recent years, titanium dioxide is widely used in photocatalysis, lithium ion battery and other fields because of little environmental pollution, stable chemical properties, low cost and so on. Compared with the traditional TiO2electrode materials, TiO2-B nano materials possessapp:addword:possess quite high theoretical specific capacity (335mA h g-1) and very outstanding rate performance as anode materials for lithium ion batteries due to its lattice channel structure and pseudo capacitance effects. In this paper, a series of TiO2nanomaterials including TiO2-B nano-flowers, N-doped TiO2-B nanorods and TiO2-B/G composites were prepared. The main research results are listed as follow:In chapter3, one-step hydrothermal methode was adapted to synthesize TiO2-B nanomaterials. Hierarchically mesoporous TiO2-B nanoflowers have been successfully synthesized by controlling the hydrothermal conditions and calcination temperature. TiO2-B nanoflowers with different degree of crystallinity are prepared at the selected calcining temperature. TiO2-B nanoflowers calcined at300℃for4h is very well crystallized, and the content of anatase TiO2is low. The electrochemical properties of TiO2-B nanoflowers were evaluated by constant current charge-discharge technology. It is found that TiO2-B nanoflowers have high discharge capacity, high rate discharge capability and good cyclic stability and reversibility.In chapter4, TiO2B nanorods were prepared via hydrothermal method, and the subsequently modified by nitrogen doping, the as-prepared TiO2-B sample with the length of about2μm and the width of about100nm showed good cycle stability (92.4%capacity retention) and rate performance (153mAh g-1at10C). The1D nanorods structure can shorten the transmission path of Li+, promote Li+diffusion rate, which lead to good electrochemical performance. Lithium storage performance of nitrogen doped TiO2-B nanorods decreases than that of pure TiO2-B, it may be due to the fact that the nitrogen doping destroyed the original pore structure.In chapter5, graphene oxide (GO) was prepared by Hummers method, and TiO2-B samples was prepared by using P25and15M NaOH solution as raw materials. The GO was reduced to graphene by hydrazine hydrate, dispersed and added into the TiO2-B materials. The mixture was dried and grinded after ultrasonic dispersion to get TiO2-B/G composite. By contrast, the TiO2-B/G composites possess more excellent specific capacity and rate capability than pure TiO2-B nanomaterials. The capacity of TiO2-B/G composites can reach about240mAh g-1(1C), and still can maintain201mAh g-1when the rate is up to10C, which is due to the fact that the graphene has excellent electrical transport properties, large specific surface area and high conductivity etc.