Monodispersed FeS2 Electrocatalyst Anchored to Nitrogen-Doped Carbon Host for Lithium-Sulfur Batteries

Despite their high theoretical energy density, lithium-sulfur (Li-S) batteries are hindered by practical challenges including sluggish conversion kinetics and shuttle effect of polysulfides. Here, a nitrogen-doped continuous porous carbon (CPC) host anchoring monodispersed sub-10 nm FeS2 nanoclusters (CPC@FeS2) is reported as an efficient catalytic matrix for sulfur cathode. This host shows strong adsorption of polysulfides, promising the inhibition of polysulfide shuttle and the promoted initial stage of catalytic conversion process. Moreover, fast lithium ion (Li-ion) diffusion and accelerated solid-solid conversion kinetics of Li2S2 to Li2S on CPC@FeS2 host guarantee boosted electrochemical kinetics for conversion process of sulfur species in Li-S cell, which gives a high utilization of sulfur under practical conditions of high loading and low electrolyte/sulfur (E/S) ratio. Therefore, the surfur cathode (S/CPC@FeS2) delivers a high specific capacity of 1459 mAh g(-1) at 0.1 C, a stable cycling over 900 cycles with ultralow fading rate of 0.043% per cycle, and an enhanced rate capability compared with cathode only using carbon host. Further demonstration of this cathode in Li-S pouch cell shows a practical energy density of 372 Wh kg(-1) with a sulfur loading of 7.1 mg cm(-2) and an E/S ratio of 4 mu L mg(-1).

Automated summary

This study reports a carbon host with efficient catalytic properties that improves the performance of the sulfur cathode in lithium-sulfur batteries. The carbon host enhances the adsorption of polysulfides, promotes the conversion process, and improves the electrochemical kinetics. The sulfur cathode exhibits high specific capacity, stable cycling, and enhanced rate capability under practical conditions.