Multifunctional FeP/Spongy Carbon Modified Separator with Enhanced Polysulfide Immobilization and Conversion for Flame‐Retardant Lithium‐Sulfur Batteries

Abstract Lithium‐sulfur batteries have been deemed as one of the most promising energy storage systems for the next‐generation batteries. However, some serious challenges hinder the commercialization, such as the shuttle effect of polysulfides and sluggish redox kinetics. Herein, novel FeP/spongy carbon (SC) composites with multiple adsorptions and catalytic sites are prepared as a modified separator. Specifically, the SC proves the structural stability and long ions/electron transmission channel. The adding of FeP can spontaneously react with polysulfides to block the shuttling and catalyze the conversion of sulfur chemistry. The formed adsorption‐diffusion‐conversion surface is beneficial to reduce the polarization and accelerate the redox kinetics. Furthermore, the FeP/SC modified separator can bring down the flammability to prove high‐safety LSBs. Benefiting from these features, the assembled cells with FeP/SC exhibits extraordinary cycling stability (526 mAh g −1 over 400 cycles at 1 C), a superior rate property with 619 mAh g −1 at 2 C. Moreover, the cells with a high areal sulfur loading of 4 mg cm −2 can maintain a capacity of 618 mAh g −1 after 150 cycles. Such a FeP/SC modified separator provides a potential commercial application for high‐safety and advanced Lithium‐sulfur batteries.