Three-Dimensional Flower-like Chalcogenides for Catalyzing Polysulfide Conversion toward High-Performance Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs), with their ultra-high theoretical energy density and abundant supply of low-cost sulfur resources, are regarded as a promising energy storage technology. However, the shuttle effect of lithium polysulfides (LiPSs) and their sluggish heterogeneous redox kinetics severely limit their practical application and commercialization. To address this core challenge, this study introduces a WSe 2 -MoSe 2 /CN heterojunction interface as a separator modification material. The heterojunction provides interfacial electronic interaction that facilitates charge transfer, while the three-dimensional flower-like architecture, high surface area, porous structure, and conductive carbon network collectively contribute to enhanced ion transport, abundant active sites, and effective polysulfide confinement. The synergy of these features accelerates the redox kinetics, suppresses the shuttle effect, and improves sulfur utilization and overall electrochemical performance. Distribution of relaxation time measurements indicate that the heterostructure effectively reduces the impedance of Li + and LiPSs diffusion; in situ UV–vis spectroscopy further confirms its excellent performance in efficiently converting high-order LiPSs into short-order LiPSs. Accordingly, LSBs fabricated with WSe 2 -MoSe 2 /CN heterojunction-decorated separators are proved to possess excellent electrochemical behavior within a wide operating temperature range. High discharge capacities of 1259 mAh g –1 (at 60 °C) and 952 mAh g –1 (at 0 °C) are achieved for the battery when operated at a 0.5 C current density during cycling; the decay rates of each capacity reach as low as 0.27 and 0.075%, respectively. Notably, a substantial areal capacity of 7.09 mAh cm –2 is still attained even under a large sulfur loading content of 6.01 mg cm –2 and a low electrolyte dosage with an E/S ratio of 6.35 μL mg –1 . This study provides valuable insights for the development of high-performance lithium–sulfur.