Hierarchical MoS2-NiS nanosheet-based nanotubes@N-doped carbon coupled with Ether-based electrolytes towards high-performance Na-ion Batteries

Hierarchical nanosheet-based MoS2–NiS nanotubes coated with N-doped carbon (MNS-HNT@NC) composites were fabricated using a template-assisted hydrothermal and post-sulfidation strategy. The composite, with a tube-like structure, is mainly constructed by ultrathin MoS2–NiS nanosheets. Such hierarchical nanosheet-based nanotubes possess high surface-to-volume ratios, which can release mechanical stress during Na ion insertion/extraction and shorten the pathways for Na ion/electron transport. Furthermore, the internal void space in the nanotube can effectively accommodate the large volume change of the electrode, thereby alleviating structural collapse of the electrode. On the other hand, abundant lattice defects and the internal electric field induced by the heterostructure of MoS2 and NiS boost the Na ion intercalation kinetics. In addition, the MoS2 and NiS nanocrystals uniformly dispersed in the composite can act as mutual spacers, thereby avoiding aggregation during cycling. The MNS-HNT further coated with N-doped carbon can reduce contact resistance and restrict the large volume change, preventing electrode pulverization. Benefiting from these advantages and using an ether-based electrolyte, MNS-HNT@NC, as anode for SIBs, delivers a considerable specific capacity (707 mA h g−1 at 0.1 A g−1), high initial coulombic efficiency of 94%, stable long-term cycling stability (391 mA h g−1 maintained after 700 cycles at 2 A g−1) and superior rate performance (342 mA h g−1 at 10 A g−1).