Boosting solid-solid conversion kinetics of sulfurized polyacrylonitrile via MoS2 doping for high-rate and long-life Li-S batteries

Sulfurized polyacrylonitrile (SPAN) with a "solid-solid" conversion mechanism in carbonated-based electrolyte eradicating the polysulfides shutting issue is considered as an ideal cathode for stabilizing lithium-sulfur (Li-S) batteries. However, the sluggish reaction kinetics and less sulfur content of the SPAN limit its practical application. Herein, the MoS2 doped SPAN (MoS2@SPAN) is demonstrated to rapidly accelerate the solid-solid conversion kinetics of SPAN for remarkably boosting high-power and long-life Li-S batteries. Benefitting from the accelerated lithium-ion (Li+) transfer rate, a fast ion transport channel and enhanced redox reaction kinetics of sulfur to Li2S2/Li2S is realized via MoS2 catalysis, and excellent electrochemical performance is achieved. Consequently, MoS2@SPAN delivers a high capacity of 626 mAh g(-1) at 0.1 A g(-1), and simultaneously shows ultralong cycling life of 500 cycles with only 0.089% capacity decay rate at 2 A g(-1). Moreover, a superb capacity of 321 mAh g(-1) at ultrahigh current density of 5 A g(-1) is offered, outperforming most of the reported SPAN cathodes. This work provides a general and reliable strategy on the reliable design of SPAN cathode for high-rate and long-term Li-S batteries.