Carbon-Coated Mesoporous Fe3o4 Nanospindles with Interconnected Porosities as Polysulfide Mediator for Lithium-Sulfur Batteries

Lithium-sulfur batteries are plagued by the shuttle effect and sluggish kinetics in the redox reaction of lithium polysulfides (LiPSs) to Li2S, resulting in a limited capacity and shortened lifetime. To address these issues, it is crucial to develop an efficient catalytic sulfur host by creating active sites that can both confine LiPSs and accelerate their conversion. Herein, we developed carbon-coated mesoporous Fe3O4 (C@M−Fe3O4) nanospindles and applied them as sulfur host material to improve the electrochemical performance of Li–S batteries. Besides, the conductive C@M−Fe3O4 particles with rich sites of electrolyte/Fe3O4/carbon ‘‘triple-phase’’ can also accelerate the conversion of LiPSs and promote the nucleation and growth of Li2S. With these merits, our C@M-Fe3O4/S electrode shows good cycling stability with a remaining capacity of 1064.3 mAh/g at 0.2 C after 100 cycles and delivers an initial capacity of 712.0 mAh/g at 2 C. The proposed synthetic method could pave the way for designing similar porous transition metal-based compounds with different precursors (e.g. carbonates, hydroxides, oxalates) for other electrochemical applications.