A Dual‐Carbon Phase‐Modified and Nanostructured Nickel Sulfide Anode for Sodium‐Ion Batteries

In this report, based on the concept of nanoconfinement a synthetic strategy is developed to construct an ultrathin carbon film coated nickel sulfide anchored on carbon nanotubes (CNTs) (CNT@NiS/C). The synthesis involves direct growth of nickel hydroxide on the CNTs followed by dehydration, sulfidation, and carbon coating. When used as an anode material in sodium-ion batteries (SIBs), the nickel sulfide-based anode shows a high utilization rate of active material and a favorable reversible capacity of 390 mAh g-1. The excellent performance of the nickel sulfide-based anode in SIBs demonstrates the potential of nickel sulfide to be used as the anode material in SIBs when it is engineered in a nanoconfinement environment to overcome its structural constraints. In principle, this strategy can be conveniently adapted to engineer other transition metal-based materials for applications in energy storage.