DFT-Guided\nDesign of Dual Dopants in Anatase TiO<sub>2</sub> for Boosted Sodium\nStorage

Anatase titanium dioxide (TiO<sub>2</sub>) has drawn\ngreat attention\nas an anode material in sodium ion batteries (SIBs), but it suffers\nfrom the sluggish diffusion kinetics of Na<sup>+</sup> within TiO<sub>2</sub> and inferior electronic conductivity. Herein, under the guidance\nof density functional theory (DFT), we propose a nitrogen and selenium\ndual-doped TiO<sub>2</sub> system as an advanced SIB anode. Both DFT\nand experimental investigations reveal the cooperative effect of dopants\nin boosting the electrochemical performance of TiO<sub>2</sub>, finding\nthe optimal content ratio (N/Se at 1:3) for overall improved SIB performances.\nAs expected, experimental results exhibit excellent sodium storage\nbehavior of the N,Se-doped TiO<sub>2</sub>, including high discharge\ncapacity (142 mAh g<sup>–1</sup> at 2 A g<sup>–1</sup>), good rate performance (82 mAh g<sup>–1</sup> at 20 A g<sup>–1</sup>), and ultralong cyclability (97% retention over 5000\ncycles at 2 A g<sup>–1</sup>). Our study underscores the importance\nof dual-heteroatom doping in the rational design of advanced electrode\nmaterials.