Hydrothermal synthesis of layered Li1.81H0.19Ti2O5•xH2O nanosheets and their transformation to single-crystalline Li4Ti5O12 nanosheets as the anode materials for Li-ion batteries

Lithium titanate oxide hydrate (Li1.81H0.19Ti2O5 center dot xH(2)O) nanosheets were prepared via simple hydrothermal treatment of the low cost tetrabutyl titanate in LiOH solution. The orthorhombic Li1.81H0.19Ti2O5 center dot xH(2)O nanosheets with thickness less than 10 nm were single crystalline and grew along the (100) facet. Time-dependent experiments confirmed that the formation of Li1.81H0.19Ti2O5 center dot xH(2)O nanosheets underwent a hydrolysis-Kirkendall effect-Ostwald ripening process. As these Li1.81H0.19Ti2O5 center dot xH(2)O nanosheets calcined at 500 degrees C for 2 h, the Li4Ti5O12 nanosheets with thickness of 10-20 nm were synthesized. The Li4Ti5O12 nanosheets were single crystalline and grew along the (110) facet. As an anode material for rechargeable lithium-ion batteries, Li4Ti5O12 nanosheets delivered an initial discharge capacity of 183 mAh g(-1) together with a discharge capacity of 160 mAh g(-1) after 100 cycles at 1 C. The discharge capacity could reach up to 120 mAh g(-1) even after 300 cycles at 10 C. The morphology of nanosheets with large BET value (155.5 m(2) g(-1)) and the high lithium-ion diffusion coefficient (1.51 x 10(-8) cm(2) s(-1)) could be favorable for the enhanced high-rate performance.