Disulfide-Assisted Organic Polysulfide Cathode Design Enables Improved Kinetics in Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) is fundamentally limited by the “shuttle effect” and poor kinetics. To address these challenges, this study proposes an approach through developing a novel organic polysulfide composite cathode with high sulfur loading. By implementing a radical reaction between elemental sulfur and a disulfide of tetramethylthiuram disulfide (TMTD), linear organic polysulfides (TMTD-S) containing over 70 wt% sulfur are successfully synthesized. This kind of material features a covalently bonded R-Sn-R (R=C₂H₆N(S)) backbone. Further compounding with the conductive carbon (ECP600JD) and integrating into a paper-based electrode help to improve the electrode's conductivity and optimized ion transport pathways. The obtained TMTD-24S@ECP600JD cathode demonstrates a capacity retention rate of 79.1% after 250 cycles at 0.2C, far superior to traditional S@ECP600JD materials (14.1%). By increasing the sulfur content in TMTD, higher sulfur-content linear organic polysulfides are also obtained. Among them, the TMTD-54S@ECP600JD with 88 wt% sulfur content exhibits the best electrochemical performance and the highest lithium-ion diffusion coefficient, delivering an initial discharge capacity of 941 mAh g⁻¹ at 0.2C, with a capacity retention rate of 82.1% after 200 cycles. Even at a high rate of 2C, it still maintained a high specific capacity of 638.3 mAh g⁻¹, making it a potential material for high-performance Li-S batteries.