Hydrogenated Oxygen-Deficient Blue Anatase as Anode for High-Performance Lithium Batteries

Abstract

Blue oxygen-deficient nanoparticles of anatase TiO₂ (H-TiO₂) are synthesized using a modified hydrogenation process. Scanning electron microscope and transmission electron microscope images clearly demonstrate the evident change of the TiO₂ morphology, from 60 nm rectangular nanosheets to much smaller round or oval nanoparticles of ∼17 nm, after this hydrogenation treatment. Importantly, electron paramagnetic resonance and positronium annihilation lifetime spectroscopy confirm that plentiful oxygen vacancies accompanied by Ti³⁺ are created in the hydrogenated samples with a controllable concentration by altering hydrogenation temperature. Experiments and theory calculations demonstrate that the well-balanced Li⁺/e^– transportation from a synergetic effect between Ti³⁺/oxygen vacancy and reduced size promises the optimal H-TiO₂ sample a high specific capacity, as well as greatly enhanced cycling stability and rate performance in comparison with the other TiO₂