Large-Scale Synthesis of N,S Codoped Carbon-Modified Fe0.975S 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 (Fe0.975S) nanohybrids, augmented by N,S codoped carbon. The resulting N,S codoped carbon-coated Fe0.975S (Fe0.975S@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//Fe0.975S@NSC and Na3V2(PO4)3//Fe0.975S@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 Fe0.975S@NSC composite.

An innovative double-Shell layer nitrogen and sulfur co-doped carbon-Encapsulated FeS composite for enhanced lithium-Ion battery performance.

FeS, with its high theoretical capacity and natural abundance, holds significant promise as an anode material for lithium-ion batteries (LIBs). However, its practical application is constrained by poor electrical conductivity and substantial volume expansion during cycling, which impair charge-discharge efficiency and cycling stability. To overcome these challenges, we developed a nitrogen and sulfur co-doped carbon-encapsulated FeS composite with a hollow double-layer structure (HDL-FeS@NSC). Utilizing sulfur spheres as a sacrificial template, our inside-out synthesis strategy produces a unique material design. The HDL-FeS@NSC composite exhibits significant improvements in electrochemical performance compared to pure FeS. These enhancements are due to its increased specific surface area, which facilitates lithium-ion diffusion; a shortened Li+ diffusion pathway; structural stability that mitigates volume expansion; and an optimized carbon layer that boosts conductivity. The HDL-FeS@NSC-70 anode demonstrates a specific capacity of 879.6 mAh/g after 600 cycles at 1.0 A/g and retains 558.0 mAh/g at 5.0 A/g. Additionally, the lithium storage mechanism has been thoroughly investigated using in-situ techniques. These results suggest that the HDL-FeS@NSC composite anode has the potential to significantly enhance lithium-ion battery performance, offering a promising solution for next-generation energy storage systems.