An efficient Se-doping strategy to boost sodium storage capacity of anatase TiO2 nanospheres

Titanium dioxide (TiO2) with a suitable voltage platform and superior structure stability has captured extensive attention as the anode for sodium-ion batteries (SIBs), but the inferior electronic conductivity and sluggish diffusion rate of Na+ impede its widespread application. Herein, selenium (Se) was firstly selected as a dopant to ameliorate intrinsic electronic conductivity and create defects on the surface of TiO2. Se-doped TiO2 anode delivers an attractive sodium storage capacity, including a high initial charge capacity of 313.6 mAh g−1 at 0.1 A g−1, superior rate capacity (107.2 mAh g−1 at 10.0 A g−1), and outstanding cycling durability (155.3 mAh g−1 at 1.0 A g−1 after 3000 cycles). Furthermore, theoretical calculations indicate that Se doping can significantly elevate the electronic conductivity of TiO2 and induce the redistribution of charge around doping sites which produces the local electric field and facilitates fast charge transfer during the discharge/charge process. Taking the relatively huge radius and electronic conductivity of Se into consideration, Se-doped TiO2 was adopted to enhance the intrinsic electronic conductivity and sodium ion diffusion rate of TiO2 as well as induce the redistribution of charge. [Display omitted]