Preparation of carbon-coated TiO2 nanostructures for lithium-ion batteries

Carbon-coated TiO2 one-dimensional nanostructures are synthesized by hydrothermal reaction followed by post-calcination at various temperatures. Post-calcination induces crystallization of TiO2 and the complete crystallization of anatase phase is observed at 600 °C of the calcination temperature. Carbon-coated TiO2 nanostructures show relatively poor crystallinity as compared with the pristine counterparts, but their lithiation capacity and high rate capability are improved throughout all calcination temperatures. The coated carbon suppresses severe agglomeration of TiO2 nanotubes which allows easy access of Li-ions and electrons to the whole surface of primary nanotubes, leading to the better lithiation performance. Higher calcination temperatures cause excessive growth of nanotube walls, leading to the collapse of tubular morphology and deterioration of lithiation performance. At 700 °C of the calcination temperature, the enhanced electronic conductivity from the graphitization of the coated carbon seems to be the main reason for the improved capacity of TiO2 nanowires.This work was supported by National Research Foundation of Korea (NRF) grant funded by the Korean Government (MEST) (No. 2010-0022325). Center for Scientific Instrument of Andong National University for the SEM, TEM, and XRD measurements is greatly acknowledged