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

Abstract

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.