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

Abstract Owing to the large interlayer spacing and the excellent theoretical capacity of MoSe 2 , it has great potential to be applied as an anode material for sodium‐ion batteries. However, the rate performance of MoSe 2 is strongly limited by the insufficient intrinsic electron transfer kinetics. Herein, a simple two‐step hydrothermal method to construct MoSe 2 /Bi 2 Se 3 heterostructures was developed by growing MoSe 2 nanosheets onto Bi 2 Se 3 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 MoSe 2 /Bi 2 Se 3 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 MoSe 2 /carbon composites. It also can compare with some of the MoSe 2 ‐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 Bi 2 Se 3 (work function is 5.61 eV) and MoSe 2 (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.