LAUSR

Abstract Titanium dioxide bronze (TiO 2 -B) nanowires were prepared by the hydrothermal method and used as the positive electrode for Mg rechargeable batteries and Li + /Mg 2+ hybrid-ion batteries. First-principles calculations showed that the diffusion barrier for Mg 2+ (0.6 eV) in the TiO 2 -B lattice was more than twice of that for Li + (0.3 eV). Electrochemical impedance spectroscopy showed that the charge transfer resistance of TiO 2 -B in the Mg 2+ ion electrolyte was much larger than that in the Li + /Mg 2+ hybrid electrolyte. For these reasons, the Mg rechargeable battery showed a small discharge capacity of 35 mAh g −1 resulting from an electrochemical double-layer capacitive process. In comparison, the TiO 2 -B nanowires exhibited a large capacity (242 mAh g −1 at the 20 mA g −1 current density), high rate capability (114 mAh g −1 at 1 A g −1 ), and excellent cycle stability in the Li + /Mg 2+ hybrid-ion battery. The dominant reaction occurred in the TiO 2 -B electrode was intercalation of Li + ions, of which about 74% of the total capacity was attributed to Li + pseudo-capacitance.