Safe, Facile, and Straightforward Fabrication of Poly(N-vinyl imidazole)/Polyacrylonitrile Nanofiber Modified Separator as Efficient Polysulfide Barrier Toward Durable Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are gaining tremendous attention as promising energy storage solutions due to their impressive energy density and the affordability of sulfur. However, the practical use of Li–S batteries encounter major obstacles such as the polysulfide shuttle effect, which leads to capacity loss and decreased cycling stability. Herein, a polyethylene imidazole/polyacrylonitrile (PVIMPAN) nanofibers-modified Celgard separator is constructed via a facile electrospinning strategy and used as a polysulfides barrier for Li–S batteries. The electron-deficient imidazole groups introduced on the surface of PVIMPAN separators create a barrier that prevents polysulfide shuttling and extends cycle life. Additionally, the developed PVIMPAN separator exhibits a significantly enhanced Li⁺ transfer number of 0.60, compared to the commercial Celgard separator (0.20). This enhancement can be attributed to the strong binding energy between imidazole groups and bis(trifluoromethanesulphonyl)imide anion, leading to improved Li plating and stripping performance. Consequently, incorporating the PVIMPAN separator into Li–S batteries enable the achievement of a discharge capacity of 786.0 mAh g⁻¹ with close to 100% Coulombic efficiency after 500 cycles at 1C (25 °C). It is believed that this work can provide valuable insights for designing suitable and robust separators for metal–sulfur batteries.