Simultaneous Efficient Polysulfide Adsorption and Bidirectional Catalysis Enabled by a Multifunctional Separator for Advanced Lithium–Sulfur Batteries

Abstract

The commercial deployment of lithium–sulfur batteries remains largely obstructed by the notorious shuttling behavior of lithium polysulfides (LiPSs) alongside their slow redox kinetics. Herein, a synergistic heterostructure composed of SnS and CoS nanoparticles (SnS-CoS@rGO) is developed as a multifunctional interlayer for separator modification. The SnS-CoS@rGO heterojunction integrates the strong chemisorption capability of SnS and the superior catalytic efficiency of CoS, while the interfacial electric field significantly accelerates interfacial charge transfer. Consequently, the SnS-CoS@rGO-modified separator effectively traps LiPSs and promotes their rapid catalytic conversion. With the SnS-CoS@rGO separator, the Li–S battery exhibits a remarkable first-cycle discharge capacity of 1528.2 mAh g–1 at 0.1 C and maintains exceptional long-cycle durability after more than 1000 cycles at 1 C, with a mere capacity degradation rate of 0.0375% cyclically. Furthermore, the modified separator exhibits favorable lithiophilicity and flame retardancy, thereby effectively impeding the growth of lithium dendrites and enhancing the battery safety performance. This study demonstrates the potential of SnS-CoS@rGO heterostructured electrocatalysts, providing an innovative avenue for designing advanced Li–S batteries.