Hierarchical rutile TiO2 microspheres assembled by nanorods with nanocavities and their lithium-ion storage properties

Unique hierarchical rutile TiO2 microspheres assembled by nanorods with nanocavities were successfully synthesized through mesoscale assembly in the tetrabutyl titanate-hydrochloric acid system followed by subsequently calcinating in air. In contrast to the classical mechanism of atom-/molecule-mediated growth of a single crystal, the particle-mediated growth and assembly mechanism was summarized as nonclassical crystallization. The particle-based crystallization pathways lead to single crystals with nanocavities via mesoscopic transformation and anti-nucleation process. The electrochemical properties were investigated by constant current discharge-charge tests and electrochemical impedance techniques. This microsphere-shaped rutile TiO2 with nanocavities exhibits excellent rate capacities (151 mAh g−1 at 2 C) and better cyclic performance than that of rutile TiO2 mesocrystals precursor at high rate.