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

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.