Rapid Charge-Discharge Property of Li4Ti5O12-TiO2 Nanosheet and Nanotube Composites as Anode Material for Power Lithium-Ion Batteries

Well-defined Li4Ti(5)O(12)TiO(2) nanosheet and nanotube composites have been synthesized by a solvothermal process. The combination of in situ generated rutileTiO(2) in Li4Ti(5)O(12) nanosheets or nanotubes is favorable for reducing the electrode polarization, and Li4Ti(5)O(12)TiO(2) nanocomposites show faster lithium insertion/extraction kinetics than that of pristine Li4Ti(5)O(12) during cycling. Li4Ti(5)O(12)TiO(2) electrodes also display lower charge-transfer resistance and higher lithium diffusion coefficients than pristine Li4Ti(5)O(12). Therefore, Li4Ti(5)O(12)TiO(2) electrodes display lower charge-transfer resistance and higher lithium diffusion coefficients. This reveals that the in situ TiO2 modification improves the electronic conductivity and electrochemical activity of the electrode in the local environment, resulting in its relatively higher capacity at high chargedischarge rate. Li4Ti(5)O(12)TiO(2) nanocomposite with a Li/Ti ratio of 3.8:5 exhibits the lowest charge-transfer resistance and the highest lithium diffusion coefficient among all samples, and it shows a much improved rate capability and specific capacity in comparison with pristine Li4Ti(5)O(12) when charging and discharging at a 10 C rate. The improved high-rate capability, cycling stability, and fast chargedischarge performance of Li4Ti(5)O(12)TiO(2) nanocomposites can be ascribed to the improvement of electrochemical reversibility, lithium ion diffusion, and conductivity by in situ TiO2 modification.