Regulating Polysulfide Transformation and Stabilizing Lithium Anode Using [PMo₁₂O₄₀]^3- Cluster@Carbon Nanotube-Modified Separator for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries emerge as compelling contenders for next-generation energy-storage devices, boasting a noteworthy mass-specific energy of 2600 Wh kg(-1). However, the cycle stability and commercialization of Li-S batteries encounter challenges because of polysulfide shuttle and uncontrolled lithium dendrite growth. In this study, we present a polyoxometalates-based dual-function [PMo12O40](3-) cluster@carbon nanotube modified polypropylene (PP) separator (PMo12@CNT/PP) to regulate polysulfide transformation and safeguard the lithium anode in Li-S batteries. Leveraging its multi-electron redox properties and stable cluster structure, the PMo12 cluster acts as a polysulfide mediator, effectively capturing and promoting electrochemical polysulfide transformation. The incorporation of CNT fosters consistent Li-ion nucleation, stabilizes the lithium anode, and impedes dendrite formation throughout cycling. Hence, Li-S cells equipped with the PMo12@CNT/PP separator display higher capacity and better stability (675 mAh g(-1) at 3.0 C and 0.02 % capacity decay per cycle over 700 cycles). The pouch cells with a sulfur loading 4.5 mg cm(-2) exhibit an initial discharge specific capacity of 925 mAh g(-1) at 0.1 C, and remain 849 mAh g(-1) after 40 cycles, underscoring the significant potential for practical applications of Li-S batteries.