Facile template-free preparation of hierarchical TiO2 hollow microspheres assembled by nanocrystals and their superior cycling performance as anode materials for lithium-ion batteries

Abstract

The design and fabrication of hierarchical TiO₂ hollow structures assembled by nanosized building blocks have been proven to be an effective strategy for significantly improving the electrochemical performance of TiO₂-based anodes for lithium-ion batteries, which can be attributed to the increased surface lithium storage. Herein, uniformly distributed hierarchical anatase TiO₂ hollow microspheres assembled by nanocrystals with an average size of 10–20 nm (denoted as TiO₂ HMs) have been successfully prepared via a facile template-free one-pot hydrothermal process. The possible formation mechanism of TiO₂ HM is also investigated by time-dependent and ammonium fluoride (NH₄F) concentration-dependent experiments. Moreover, our strategy is simpler than other generally template-involved methods as it effectively avoids the tedious preparation and removal process of templates, and the time-consuming heating treatment for crystallization. As a promising anode material for lithium-ion batteries, TiO₂ HMs exhibit excellent electrochemical performances in terms of high capacity, ultra-long cycling stability and good rate capability. After 1000 cycles, a capacity of 150.7, 129.9 and 104.5 mA h g⁻¹ is retained at 1, 5 and even 20 C, respectively. The peculiarly hierarchical hollow structure should be responsible for the excellent performances.