Engineering a Phosphazene-Based Hollow Rod-Like Lanthanum-MOF: A Strategy for Controlling Polysulfides Shuttle Effect in Li–S Batteries

Lithium–sulfur (Li–S) batteries have garnered attention as next-generation energy storage systems owing to their exceptionally high energy density. However, practical deployment is hindered by challenges such as lithium dendrite formation, polysulfide shuttling, and lethargic sulfur redox kinetics, which limit the rate capability, cycle life, and areal capacity, particularly at high sulfur loadings. In this paper, we present a methodology for fabricating a modified separator by coating a phosphazene-derived lanthanum-based metal–organic framework (La-MOF) onto a polypropylene separator. The La-MOF exhibits a high specific surface area, hierarchical porosity, and excellent thermal stability. Adsorption studies demonstrate its strong affinity for lithium polysulfides (LiPSs), facilitating their immobilization while enabling uniform Li + transport through well-defined nanochannels. Additionally, the La-MOF provides active sites for the electrocatalytic conversion of LiPSs, effectively mitigating the shuttle effect. The resulting Li–S cells equipped with a La-MOF-modified PP separator deliver an initial discharge capacity of 1109 mAh g –1 with stability over 500 cycles at 1C. This protocol outlines a scalable approach for separator modification, offering a pathway toward high-performance Li–S batteries with improved stability and efficiency.