Sulfurization accelerator coupled Fe1−xS electrocatalyst boosting SPAN cathode performance

Sulfurized polyacrylonitrile (SPAN) cathode exhibits improved cycling stability in carbonate electrolytes due to the existent of −S 2− − (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, Fe1−xS is in situ converted from FeCl3, which acts as the electrocatalyst to promote Li2S nucleation and decomposition reactions. As a result, the Fe1−xS/SPAN/rGO electrode with high sulfur loading of 2.0 mg·cm−2 delivers a reversible capacity of 1122 mA·hg−1 at 0.1 A·g−1. Notably, at a large current density of 5.0 A·g−1, the Fe1−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.