Interfacial “Double-Terminal Binding Sites” Catalysts Synergistically Boosting the Electrocatalytic Li₂S Redox for Durable Lithium–Sulfur Batteries

Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium–sulfur (Li–S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li–S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li–S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g–1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm–2 even in challenging conditions with a high sulfur loading (10.7 mg cm–2) and lean electrolyte environments (5.8 μL mg–1). The DTB site strategy offers valuable insights into the development of high-performance Li–S batteries.