Hierarchical Nanotube-Constructed Porous TiO₂-B Spheres for High Performance Lithium Ion Batteries

Hierarchically structured porous TiO₂-B spheres have been synthesized via a hydrothermal process using amorphous titania/oleylamine composites as a self-sacrificing template. The TiO₂-B spheres are constructed by interconnected nanotubes and possess a high specific surface area of 295 m 2 g ^-1. When evaluated as an anode material in lithium-half cells, the as-obtained TiO₂-B material exhibits high and reversible lithium storage capacity of 270 mA h g ^-1 at 1 C (340 mA g ^-1), excellent rate capability of 221 mA h g ^-1 at 10 C, and long cycle life with over 70% capacity retention after 1000 cycles at 10 C. The superior electrochemical performance of TiO₂-B material strongly correlates to the synergetic superiorities with a combination of TiO₂-B polymorph, hierarchically porous structure, interconnected nanotubes and spherical morphology. Post-mortem structural analyses reveal some discrete cubic LiTiO₂ nanodots formed on the outer surfaces of TiO₂-B nanotubes, which might account for the slight capacity loss upon prolonged electrochemical cycling.