DFT-Guided Design of Dual Dopants in Anatase TiO2 for Boosted Sodium Storage

Abstract

Anatase titanium dioxide (TiO₂) has drawn great attention as an anode material in sodium ion batteries (SIBs), but it suffers from the sluggish diffusion kinetics of Na⁺ within TiO₂ and inferior electronic conductivity. Herein, under the guidance of density functional theory (DFT), we propose a nitrogen and selenium dual-doped TiO₂ system as an advanced SIB anode. Both DFT and experimental investigations reveal the cooperative effect of dopants in boosting the electrochemical performance of TiO₂, finding the optimal content ratio (N/Se at 1:3) for overall improved SIB performances. As expected, experimental results exhibit excellent sodium storage behavior of the N,Se-doped TiO₂, including high discharge capacity (142 mAh g^–1 at 2 A g^–1), good rate performance (82 mAh g^–1 at 20 A g^–1), and ultralong cyclability (97% retention over 5000 cycles at 2 A g^–1). Our study underscores the importance of dual-heteroatom doping in the rational design of advanced electrode materials.