Sulfurization accelerator coupled Fe_1−xS electrocatalyst boosting SPAN cathode performance

Sulfurized polyacrylonitrile (SPAN) cathode exhibits improved cycling stability in carbonate electrolytes due to the existent of –S_x²⁻– (2 ≤ n ≤ 4) units. However, it is still challenging for SPAN to achieve higher sulfur content, superior conductivity, and faster polysulfide conversion kinetics in ether electrolytes. Herein, polyacrylonitrile (PAN), 2-morpholinothiobenzothiazole (MBS), and FeCl₃ coated reduced graphene oxide (rGO) were used to fabricate advanced sulfur cathode through electrospinning technology to address these problems. During PAN sulfuration reactions, the MBS with abundant unsaturated bonds served as the vulcanization accelerator to facilitate the formation of longer chain sulfur species (–S₃–/–S₄–) and increase the sulfur content in the SPAN electrode system. Meanwhile, Fe_1−xS is in situ converted from FeCl₃, which acts as the electrocatalyst to promote Li₂S nucleation and decomposition reactions. As a result, the Fe_1−xS/SPAN/rGO electrode with high sulfur loading of 2.0 mg·cm⁻² delivers a reversible capacity of 1122 mAh·g⁻¹ at 0.1 A·g⁻¹. Notably, at a large current density of 5.0 A·g⁻¹, the Fe_1−xS/SPAN/rGO electrode still displays a high specific capacity of 924 mAh·g⁻¹ with an ultra-stable cycling life over 2000 cycles. The present work provides new insights into designing of high-performance electrode materials for long-lasting Li-S batteries.