Facile Aluminum Reduction Synthesis of Blue TiO₂ with Oxygen Deficiency for Lithium-Ion Batteries

An ultrafacile aluminum reduction method is reported herein for the preparation of blue TiO₂ nanoparticles (donated as Al-TiO₂, anatase phase) with abundant oxygen deficiency for lithium-ion batteries. Under aluminum reduction, the morphology of the TiO₂ nanosheets changes from well-defined rectangular into uniform round or oval nanoparticles and the particle size also decreases from 60 to 31nm, which can aggressively accelerate the lithium-ion diffusion. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) results reveal that plentiful oxygen deficiencies relative to the Ti³⁺ species were generated in blue Al-TiO₂; this effectively enhances the electron conductivity of the TiO₂. X-ray photoelectron spectrometry (XPS) analysis indicates that a small peak is observed for the Al-O bond, which probably plays a very important role in the stabilization of the oxygen deficiencies/Ti³⁺ species. As a result, the blue Al-TiO₂ possesses significantly higher capacity, better rate performance, and a longer cycle life than the white pure TiO₂. Such improvements can be attributed to the decreased particle size, as well as the existence of the oxygen deficiencies/Ti³⁺ species.