Sodium alginate regulated MXene dispersion in electrospun PVA networks for flame resistant lithium-sulfur battery...

Lithium-sulfur (Li-S) batteries have emerged as promising next-generation energy storage systems due to their exceptional energy density and specific capacity. However, safety challenges hinder commercialization, including the low flash point of ether-based electrolytes, hazards from black powder-like substances formed by sulfur, nitrate, or carbon components, and insufficient thermal stability of polypropylene (PP) separators. In this study, we utilize electrospun poly(vinyl alcohol) (PVA)@MXene as the nanofiber skeleton, while sodium alginate (SA) serves as a dual-function modifier and dispersion stabilizer. The as-prepared SA-reinforced PVA@MXene membranes (SA/PMM) exhibit enhanced flame retardancy and outstanding electrochemical performance. The Li-S battery assembled with the SA/PMM separator delivers an initial discharge specific capacity of 1076.6 mAh g at 0.2C. Additionally, the cell shows an average capacity decay rate of only 0.143% per cycle after 200 cycles, while maintaining a coulombic efficiency above 99% throughout. Furthermore, the separator can endure temperatures of up to 300 ^∘C for 7 seconds when exposed to an alcohol lamp flame, with a thermal contraction rate of less than 10%. This study provides a new route for developing composite separators with high safety, high stability, and high performance, which is of great significance for promoting the practical application of lithium-sulfur batteries.