Hierarchically structured porous TiO₂ spheres constructed by interconnected nanorods as high performance anodes for lithium ion batteries

Hierarchically structured porous anatase TiO<inf>2</inf> spheres have been fabricated by a facile chemical route. The TiO<inf>2</inf> spheres are constructed by interconnected nanorods and possess a three-dimensional (3D) interpenetrating porous framework. When evaluated as an electrode material in lithium half-cells, such hierarchically porous TiO<inf>2</inf> nanostructures exhibit high lithium storage capacity (225mAhg^-1 at 0.5 C), excellent rate performance (141mAhg^-1 at 5 C), and long cycle life (an initial Li⁺ storage capacity of 187mAhg^-1 at 1 C and a capacity retention of ca. 95% after 100 cycles). The improved electrochemical properties of TiO<inf>2</inf> spheres can be attributed to the synergetic effects of their unique hierarchical structure, high surface area, large and opened pore structure and interconnected 3D network. These unique structural characteristics effectively improve the mass transfer capability of electrolyte, reduce the Li ions diffusion paths and increase the electronic conduction as well as structural stability.