Improved ions storage performance for various batteries: Anatase TiO2 with high-concentration of Ti vacancies

Anatase TiO2 is a promising anode material due to its high stability during the electrochemical process. Nevertheless, the slow diffusion coefficient of the metallic ions and insufficient storage sites seriously prevent its further applications in "beyond Li-ion" batteries (such as Na- and Mg-ion batteries). Herein, we prepare the anatase TiO2 with high-concentration Ti vacancies (TiO2–V) electrode through a simple solvothermal and subsequent calcination process. The XRD Rietveld, Electron Paramagnetic Resonance (EPR), Hall effect, Nuclear Magic Resonance (NMR) and X-ray Photoelectron Spectroscopy (XPS) are carried out to characterize the Ti vacancies. The TiO2–V delivers better battery performance than the stoichiometric anatase (TiO2–S) for storing various metallic ions (Li+/Na+/Mg2+). The Ti vacancies can act as additional ion storage sites and provide more open channels for metal ions transfer. This work systematically investigates the effect of Ti cation vacancies on the performance of metal-ion batteries and expands the application of cation vacancies.