Abstract
Exploring bimetallic sulfides of diverse metal species with well-defined nanoarchitectures and distinctive interfacial interactions is indispensable for advanced sodium-storage systems in achieving rapid electron/ion transfer kinetics, optimizing structural durability, and enhancing electrochemical energy storage. In this regard, the fabrication of a spindle-like hierarchical hollow nanocage with the dual heterointerfaces was reported utilizing N, S co-doped carbon support encapsulating hollow FeS2/NiS heterojunction (FeS2/NiS@N,S-C) through the critical steps of facile dopamine self-polymerization, followed by hydrolyzation, carbonization and further sulphuration. Benefiting from the great superiorities of superior conductivity, excellent structural robustness, abundant active reaction sites, efficient charge transport pathways, as well as fast ion-migration kinetics bestowed by creating an synergistically induced dual interfacial interaction in the ingenious nanoarchitecture, the FeS2/NiS@N,S-C composites render a significantly optimized comprehensive performance of Na+-storage, yielding a highly competitive capacity of 598.0 mAh g−1 after 600 cycles at 1.0 A g−1, and desirable cycle stability with supernormal rate capability (362.6 mAh g−1 after 1950 cycles at 20.0 A g−1), one of the best performances for FeS2- or NiS based heterojunctions. Meanwhile, the redox mechanism involving initial intercalation reaction and following conversion stage was uncovered detailly by a set of ex-situ experimental characterizations. Theoretical evidences drawn from density functional theory calculations illustrate that the formation of dual heterointerfaces in FeS2/NiS@N,S-C composites enables good conductivity, optimizes Na+ adsorption energy, and reduces activation energy for Na+ migration, which facilitates ion/electron migration and enhances reaction kinetics of the electrode.
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