Stabilizing NiS₂ on Conductive Component via Electrostatic Self‐assembly and Covalent Bond Strategy for Promoting Sodium Storage

AbstractThe high theoretical capacities and excellent redox activities motivate transitional metal sulfides (TMSs) to serve as promising anode materials for sodium‐ion batteries. However, TMSs would experience low electronic conductivity as well as notorious polysulfides dissolution and shuttle effect during charge/discharge processes, which leads to unsatisfactory rate capability and cycling stability. Herein, TMSs‐based anode materials with NiS2 nanoparticles tightly anchoring on nitrogen‐doped graphene (NiS2/NG) via the Ni–N covalent bond have been developed through an electrostatic self‐assembly approach between exfoliated positively charged layered double hydroxide and negatively charged graphene oxide nanosheets, followed by a sulfidation process. The strong coupling between conductive and active components enables NiS2/NG to possess good structural integrity, high ion/electron conductivity, and strong polysulfides adsorption capability, ensuring fast reaction kinetics and energetically stable performance. In consequence, the NiS2/NG delivers a high capacity of 664 mAh g−1 at 0.1 A g−1, good rate performance of 545 mAh g−1 at 2 A g−1, and excellent cycling stability with a retained capacity of 589.9 mAh g−1 after 1200 cycles at 0.5 A g−1, among the best results of reported TMSs‐based anodes. The study provides an effective strategy to design heterostructured materials with strong coupling interaction for high‐efficient‐stable sodium storage.