Hierarchical hollow mixed metal sulfides microspheres assembly from NiS nanoparticles anchored on MoS2 nanosheets and coated with N-doped carbon for enhanced sodium storage

Abstract A NiS-MoS2@N-doped carbon (HH-NMS@NC) composite is fabricated by sacrificial template, self-assembly, and post-sulfidation strategy. The NiS nanoparticles are uniformly anchored on MoS2/NC nanosheets to construct a hierarchical hollow structure, which can shorten the electrons/ions transport pathway, facilitate electrolyte infiltration, and thus enhance the electrochemical kinetics. Furthermore, the N-doped carbon coating can significantly improve the electrical conductivity and prevent the electrode pulverization during cycling due to effectively restricting the large volume change of metal sulfides. In addition, mixed metal sulfides show an intrinsic synergistic effect for enhancing sodium storage compared to single-component metal sulfides. Given these advantages, HH-NMS@NC as anode for Na-ion batteries exhibits enhanced electrochemical performance. Specifically, HH-NMS@NC can deliver an initial discharge of 488 mAh g−1 and 311 mAh g−1 retained after 700 cycles at 1 A g−1, corresponding to 0.064% capacity decay per cycle. Furthermore, it shows a superior rate capability of 377 mAh g−1 at 8 A g−1.