Orbital-Tailoring Strategy via Dual-Defect Engineering in P-FeTe_2-x@NC Synergizes Polysulfide Adsorption-Conversion...

The polysulfide shuttling and sluggish sulfur redox kinetics hinder the commercialization of lithium-sulfur (Li-S) batteries. Herein, the fabrication of phosphorus (P)-doped iron telluride (FeTe₂) nanoparticles with engineered Te vacancies anchored on nitrogen (N)-doped carbon (C) (P-FeTe_2-x@NC) is presented as a multifunctional sulfur host. Theoretical and experimental analyses show that Te vacancies create electron-deficient Fe sites, which chemically anchor polysulfides through enhanced Fe─S covalent interactions. Additionally, P doping shifts the Fe d-band center toward the Fermi level, increasing the affinity for polysulfide intermediates through d-p orbital hybridization. This dual modulation strengthens the built-in electric field at the P-FeTe_2-x/NC interface, effectively suppressing the shuttle effect and accelerating redox kinetics. The optimized P-FeTe_2-x@NC host enables Li-S batteries to achieve an initial capacity of 1475.6 mAh g^-1 at 0.1 C and remarkable cycling stability, exhibiting only a 0.031% capacity decay per cycle over 1000 cycles at 1 C. High sulfur utilization is evidenced by attaining 6.51 mAh cm^-2 areal capacity under a loading of 7.80 mg cm^-2, while a 2.67 Ah pouch cell delivers an energy density of 326.6 Wh kg^-1. This work establishes a vacancy-doping synergy strategy for coordinating adsorption and conversion processes in sulfur electrochemistry, offering new insights into the design of high-energy-density batteries.