Efficient Sulfur Host Based on Yolk-Shell Iron Oxide/Sulfide-Carbon Nanospindles for Lithium-Sulfur Batteries.

Numerous nanostructured materials have been reported as efficient sulfur hosts to suppress the problematic "shuttling" of lithium polysulfides (LiPSs) in lithium-sulfur (Li-S) batteries. However, direct comparison of these materials in their efficiency of suppressing LiPSs shuttling is challenging, owing to the structural and morphological differences between individual materials. This study introduces a simple route to synthesize a series of sulfur host materials with the same yolk-shell nanospindle morphology but tunable compositions (Fe3 O4 , FeS, or FeS2 ), which allows for a systematic investigation into the specific effect of chemical composition on the electrochemical performances of Li-S batteries. Among them, the S/FeS2 -C electrode exhibits the best performance and delivers an initial capacity of 877.6 mAh g-1 at 0.5 C with a retention ratio of 86.7 % after 350 cycles. This approach can also be extended to the optimization of materials for other functionalities and applications.