Micro-flower-like MoS2-modified Co9S8 heterostructure as anode material for sodium-ion batteries with superior reversibility and rate capacity

Designing and fabricating of heterostructured materials with long-term cycling stability and high-rate capacity for the anode of sodium-ion batteries (SIBs) still remain a great challenge. Herein, micro-flower-like MoS2-modified Co9S8 (Co9S8/MoS2) with a three-dimensional (3D) heterostructure was first obtained via a simple solvothermal synthesis followed by a solid sulfidation treatment process. As a material for the anode of SIBs, the Co9S8/MoS2-based electrode with an initial Co/Mo molar ratio of 1/1 (denoted as CM55-S) exhibits the best sodium storage performance with a boosted capacity, superior reversibility (424.5 mAh g–1@2 A g–1 at the 1600th cycle, 401.1 mAh g–1@5 A g–1 at the 800th cycle), and an excellent rate capacity (210.1 mAh g–1@20 A g–1). Density functional theory (DFT) calculations confirm that the Co9S8/MoS2 heterostructure has a lower energy barrier (0.30 eV) than the pure Co9S8 (0.53 eV). It is expected that such a heterostructured material could be an attractive candidate as the material of the anode for SIBs.