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

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.