Interface Engineering of Space-Confined Fe₃O₄/FeS Heterostructures: Synergistic Effect and Ultrastable Li Storage

Iron-based compounds, which feature the advantages ofhigh specificcapacity and inexpensive fabrication, are widely studied as promisinganode candidates for the purpose of facilitating their electricalconductivity and structural integrity. Interface engineering and structuralconfinement are verified as effective methods to improve the sluggishcharge transfer kinetics and rapid structural failure during the repeatedlithiation/delithiation processes. In this work, we proposed a simplesynthesis strategy to construct a space-confined Fe3O4/FeS heterostructure embedded in pyrolytic carbon (Fe3O4/FeS@C). The Fe3O4/FeSheterogeneous interface facilitates combination of the advantagesof each component (Fe3O4 and FeS) and constructsa built-in electric field to promote the charge transport in the Fe3O4/FeS@C anode. The space-confined structure contributesto maintaining the structural stability by buffering the volumetricvariation and suppressing the aggregation of active particles. Profitingfrom the synergism of the engineering of heterogeneous interfacesand the feature of confined structure, Fe3O4/FeS@C manifests an excellent rate capability (913.74 mA h center dot g(-1) at 200 mA center dot g(-1) and 535.79 mAh center dot g(-1) at 6400 mA center dot g(-1)) and a stable cycling performance (439.8 mA h center dot g(-1) after 1000 cycles at 3200 mA center dot g(-1)) as a competitiveanode for lithium-ion batteries. The density functional theory (DFT)calculations demonstrate that the introduction of a heterogeneousinterface enhances the adsorption of Li-ions, improves the electricalconductivity, as well as promotes interfacial electron/ion transferkinetics.