Synergistic Effect of Nitrogen and Sulfur Dual‐Doping Endows TiO2 with Exceptional Sodium Storage Performance

Abstract

AbstractImproving the diffusion kinetics of sodium ions within TiO2 and its intrinsic electronic conductivity is indispensable to enhance the rate capability and long cyclic stability of TiO2 anodes for sodium‐ion batteries. Although single‐heteroatom doping into TiO2 has been widely investigated, a comprehensive understanding of the effects of dual‐heteroatoms doping on the sodium storage performance of TiO2 is still lacking. Herein, nitrogen and sulfur dual‐doping is proposed to achieve a high doping concentration for anatase TiO2 hollow spheres. Experimental data and theoretical calculations reveal that N doping can efficiently narrow the bandgap of TiO2, while S doping is effective in facilitating Na+ diffusion within TiO2. Thus N and S codoped TiO2 shows remarkably boosted electronic conductivity, as well as accelerated sodium ion transfer kinetics owing to the synergistic effect of different doping heteroatoms, which leads to exceptional rate performance (307.5 and 156.4 mAh g−1 at 33.5 and 5025 mA g−1, respectively), and extraordinary cycling stability (90.5% retention over 2400 cycles at 3350 mA g−1). The greatly improved electrochemical performance emphasizes the importance of defects engineering in the rational design of advanced battery materials.