Vanadyl Complex-Mediated Molecular Engineering Enables Homogeneous Modulation of Lithium-Sulfur Chemistry

The large-scale commercial application of lithium-sulfur batteries (LSBs) is hindered by several critical challenges, including severe lithium polysulfide shuttling, sluggish kinetics of sulfur redox reactions, and unstable lithium anode surface. These issues significantly restrict the discharge capacity, cycling life, and safety of LSBs. Herein, the vanadyl acetylacetonate (VO) complex, characterized by a high donor number, is used as an effective homogeneous catalyst to address these cross-cutting problems. Concurrently, a functionalized separator modified with N,N'-di(propanoic acid)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) is employed to prevent the migration of VO molecules from the cathode to the anode side. The applied VO complex in the electrolyte provides completely active sites and ensures sufficient interfacial contact for homogeneously guiding the Li₂S nucleation/decomposition reactions, while optimizing the lithium anode interface. By integrating 0.1 wt.% VO complex into the electrolyte and PDI-based separator, the homogenous catalyic function of the VO catalyst is effectively pledged. As a result, the LSBs demonstrate favorable performance, achieving a capacity retention of 97.1% at 0.5 C after 100 cycles and a stable cycling at 3.0 C over 800 cycles.