Effects of F-Doping on the Electrochemical Performance of Na₂Ti₃O₇ as an Anode for Sodium-Ion Batteries.

The effects of fluorine (F) doping on the phase, crystal structure, and electrochemical performance of Na₂Ti₃O₇ are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements. F-doping does not change the crystal structure of NTO, although it has an effect on the morphology of the resultant product. As an anode material for sodium-ion batteries, the specific capacity of Na₂Ti₃O₇ exhibits a 30% increase with F-doping owing to the improved sodium ion diffusion coefficient. F-doped Na₂Ti₃O₇ also displays an enhanced rate capability and favourable cycling performance for more than 800 cycles.