Sodium-Ion Storage Properties of Thermally Stable Anatase

Anatase titanium dioxide (TiO2) is a potential anode material for sodium-ion batteries (NIBs). However, the low electronic conductivity and sluggish ion diffusion kinetics at high rate hamper its practical applications. Herein, we demonstrate a sol-gel approach to the synthesis of thermally stable anatase nanoparticles with a carbon shell as anode materials for NIBs. A sample calcined at 750 degrees C (designated as H-750TiO(2)@C) exhibits high-rate capability and excellent stability against cycling with no capacity loss after 2000 cycles at 1 A g(-1). In situ X-ray diffraction and Raman spectroscopy characterization results reveal a nearly zero-strain characteristic of the anatase phase during charge/discharge processes. In situ transmission electron microscopy, ex situ X-ray photoelectron spectroscopy, and scanning electron microscope characterization results of samples collected at different charged and discharged states suggest that the anatase phase undergoes an irreversible sodiationactivation during the initial discharge process to form a sodiated-TiO2 phase. A full cell assembled with H-750TiO(2)@C as the anode and Na3V2(PO4)(3) as the cathode delivers an energy density of 220Whkg(-1), demonstrating H-750TiO(2)@C is a potential anode material for NIBs.