The polyoxometalates-based dual-function PMo₁₂O₄₀]³⁻ cluster/carbon nanotube modified polypropylene (PP) separator (PMo₁₂@CNT/PP) can regulate LiPSs transformation by physical adsorption and electrochemically transformation rapidly, and safeguard the lithium anode in Li−S batteries. The pouch cell with PMo₁₂@CNT/PP separator cycled at 0.1 C exhibits an initial discharge capacity of 925 mAh g⁻¹ and maintains 40 cycles.

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.