Hydrogen-bond engineering of polyethylene glycol/aramid nanofiber separators via phase transition for high-safety and high-energy lithium-sulfur batteries

High performance and safety are essential prerequisites for the large-scale application of future energy storage systems. Lithium-sulfur (Li-S) batteries have garnered significant attention from the scientific community due to their high energy density and cost-effectiveness. However, challenges such as the polysulfide shuttle effect, thermal instability of commercial separators, and insufficient mechanical strength continue to hinder the commercialization of Li-S batteries. This paper presents a fabrication process for a hydrogen-bond-based polyethylene glycol (PEG)-modified aramid nanofiber (ANF) composite separator (PEG/ANF separator). The inherent properties of aramid nanofibers combined with PEG's unique flexible ether chain structure endow this separator with exceptional thermal stability (no dimensional shrinkage even at 200 °C), while also suppressing polysulfide shuttle effects and lithium dendrite growth. Results demonstrate that the PEG/ANFs separator exhibits an initial discharge specific capacity of up to 876.6 mAh·g −1 and maintains an average coulombic efficiency of 99.575 % after 300 cycles at 0.1C. This approach provides a scalable solution for designing highly safe and reliable energy storage devices. • The PEG/ANFs separator had a significant adsorption effect on polysulfides, and the adsorption energy for Li 2 S was −2.187 eV. • DFT analysis of hydrogen bonding between ANFs and PEG enhances pore uniformity to improve diaphragm flexibility and electrolyte wettability. • Ionic conductivity of Li-S battery with PEG/ANFs separator is 0.8578 mS·cm −1 electrochemical performance.