Enhancing the performance of a lithium-sulfur battery with spatially confined mesoporous nanoreactors in sulfurized polyacrylonitrile cathodes

Abstract

Sulfurized polyacrylonitrile (SPAN), which is recognized as a promising cathode material for lithium-sulfur batteries (Li-SBs), effectively mitigates the shuttle effect resulting from polysulfide dissolution. However, conventional SPAN cathodes typically exhibit sulfur loadings below 40 wt%. While encapsulation of sulfur within pores via a solid electrolyte interface addresses the low sulfur loading issue, the suboptimal kinetics of the solid–solid reactions hinder effective utilization of sulfur within the pores. In this work, Me-SeSPAN/SeS fibrous membranes were successfully synthesized through electrospinning and molten salt-assisted pyrolysis of ZIF-8, which resulted in the formation of spatially confined interconnected mesoporous nanoreactors. These nanoreactors function as supplementary storage spaces, loading and constraining the size of internal active material clusters. The fibrous membranes facilitate Li⁺ movement through pore spaces and promote adsorption of the discharge product Li₂S on the pore walls via the spatial confinement effect. Based on density functional theory (DFT) calculations, this process guarantees a supply of electrons and Li⁺ to the active material, thereby enabling continuous electron transfer during redox reactions. The optimized Me-SeSPAN/SeS electrode, featuring a sulfur and selenium loading of 70 wt%, demonstrates exceptional cycling stability in both coin and pouch cells. This study presents an effective strategy for enhancing the kinetics of active materials encapsulated in SPAN cathodes.