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

Abstract

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 LiPSs 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 2 C and retained a reversible capacity of 828 mAh g−1 after 1000 cycles, with a minimal capacity decay rate of 0.01% 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.