Large-Scale Synthesis of N,S Codoped Carbon-Modified Fe_0.975S Composites as a Novel Anode for Lithium/Sodium Ion Batteries with Enhanced Performance

To overcome obstacles hindering the commercialization of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), we introduce a cost-effective single-step sulfurization strategy for synthesizing iron sulfide (Fe_0.975S) nanohybrids, augmented by N,S codoped carbon. The resulting N,S codoped carbon-coated Fe_0.975S (Fe_0.975S@NSC) electrode exhibits exceptional potential as a highly reversible anode material for both LIBs and SIBs. With impressive initial discharge and charge capacities (1658.2 and 1254.9 mAh g^-1 for LIBs and 1450.9 and 1077.1 mAh g^-1 for SIBs), the electrode maintains substantial capacity retention (900 mA h g^-1 after 1000 cycles for LIBs and 492.5 mA h g^-1 after 600 cycles for SIBs at 1.0 A g^-1). The LiMn₂O₄//Fe_0.975S@NSC and Na₃V₂(PO₄)₃//Fe_0.975S@NSC full batteries can maintain excellent reversible capacity and robust cycling stability. Ex situ and in situ X-ray diffraction, density functional theory (DFT) calculations, and kinetics analysis confirm the promising energy storage potential of the Fe_0.975S@NSC composite.