Topological Insulator‐Assisted MoSe2/Bi2Se3 Heterostructure: Achieving Fast Reaction Kinetics Toward High Rate Sodium‐Ion Batteries.

Owing to the large interlayer spacing and the excellent theoretical capacity of MoSe2, it has great potential to be applied as an anode material for sodium‐ion batteries. However, the rate performance of MoSe2 is strongly limited by the insufficient intrinsic electron transfer kinetics. Herein, a simple two‐step hydrothermal method to construct MoSe2/Bi2Se3 heterostructures was developed by growing MoSe2 nanosheets onto Bi2Se3 nanoflakes directly. The typical topological insulator possesses ultrafast surface electronic conductivity, which makes the batteries exhibit a superior rate capability and considerable cycling stability. At a high rate of 10 A g−1, the MoSe2/Bi2Se3 electrode still delivered a superior capacity of 244 mA h g−1 (about 60 % of the discharge capacity at 0.1 A g−1), which is better than that in some of the previously reported MoSe2/carbon composites. It also can compare with some of the MoSe2‐containing complex sandwich architectures. Such unique rate performance is bound strongly with high interlayer spacing and rapid electron transfer kinetics. Besides, the different Fermi level energies of Bi2Se3 (work function is 5.61 eV) and MoSe2 (work function is 4.3 eV) probably induce a built‐in electric field nearby the heterofaces. The electric force could promote Na ions diffusibility upon cycling, leading to high reversible capacity and excellent rate performance. [ABSTRACT FROM AUTHOR]