An in situ phosphorization constructed VP2@VS2 nanoflower heterostructure with a modulated d-band center of V for efficient polysulfide adsorption and conversion in lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries, owing to their low cost, high theoretical energy density and environmental benignity, are regarded as one of the most promising candidates for next-generation green energy storage systems. However, their practical implementation faces significant challenges, particularly the shuttle effect of soluble lithium polysulfides (LiPSs) and the kinetic hysteresis during Li₂S deposition/dissociation, which severely compromise cycling stability. To address these issues, this study employs chemical vapor deposition to in situ construct a VP₂@VS₂ heterostructure with optimized interfacial characteristics on a VS₂ substrate. Experimental and theoretical results reveal that P incorporation adjusts the V d-band center, simultaneously improving LiPS chemisorption and catalyzing sulfur species conversion. This unique interfacial design facilitated bidirectional polysulfide conversion kinetics and significantly improved the nucleation and decomposition processes of Li₂S. Electrochemical tests confirmed that the VP₂@VS₂-based cathode delivered a coulombic efficiency approaching 100% at 2C and retained a reversible capacity of 828 mAh g⁻¹ after 1000 cycles, with a minimal capacity decay rate of 0.012% per cycle. Even under a high sulfur loading of 5.5 mg cm⁻², the battery exhibited exceptional cycling stability. This work proposes a novel heterointerface engineering strategy with bidirectional catalytic functionality for high-performance Li–S batteries, while offering valuable insights into interface design for other energy storage systems. Furthermore, by optimizing interfacial catalytic activity and material stability, this design significantly enhances the energy efficiency and cycling durability of batteries, thereby reducing resource consumption and environmental impact. The proposed strategy establishes a new paradigm for developing energy storage materials that combine high performance with green sustainability, advancing the practical application of clean energy technologies.