Oxygen Vacancies Enhance Lithium‐Ion Storage Properties of TiO2 Hierarchical Spheres

Abstract Titanium dioxide (TiO 2 ) is a promising electrode material for reversible lithium storage. However, the poor electronic conductivity, sluggish diffusivity, and intrinsic kinetics limit hinder its fast lithium storage capability. Here we present that the oxygen‐deficient TiO 2 hierarchical spheres can address the issues for high capacity, long‐term lithium‐ion battery anode. First‐principles calculations show that introducing oxygen vacancies to anatase TiO 2 can reduce the bandgap, thus improving the electronic conductivity and further the lithium storage properties of TiO 2 . By annealing TiO 2 /H 2 Ti 5 O 11 ⋅3H 2 O hierarchical spheres precursor in nitrogen, accompanying with the phase transfer process, the growth of TiO 2 crystallites is restricted due to the generation of residual carbon species, resulting in a well maintained hierarchical spherical structure. Rich oxygen vacancies are generated in the oxygen‐deficient environment and evidenced by EPR, XPS, and UV‐Vis spectra, which enable the TiO 2 hierarchical spheres reduced bandgap. The oxygen vacancies in the as‐obtained TiO 2 hierarchical spheres together with the high structural integrity of the hierarchical spheres gives rise to superior lithium storage properties including a high specific capacity of 282 mAh g −1 at 200 mA g −1 , and long‐term cycling stability with a capacity retention of 85.2 % at 4 A g −1 over 10000 cycles.