Nb-Doped TiO 2 with Outstanding Na/Mg-Ion Battery Performance.

The group "beyond Li-ion" batteries (Na/Mg-ion batteries) have the advantages of abundant reserves and high theoretical specific capacity. However, the sluggish kinetics resulting from large ion radius (Na + ) and polarity (Mg 2+ ) seriously limit the battery performance. Herein, we prepared Nb-doped anatase TiO 2 with Ti vacancies (Nb-TiO 2 ) through a simple solvothermal and subsequent calcination process. The Nb doping widens the channels for metal ion diffusion, and the cationic vacancies can act as ion storage sites and improve the electrode conductivity. Thus, Nb-TiO 2 exhibits improved performance for rechargeable Na/Mg-ion batteries.