Yolk@Shell Structured MnS@Nitrogen-Doped Carbon as a Sulfur Host and Polysulfide Conversion Booster for Lithium/Sodium Sulfur Batteries

Lithium-sulfur (Li-S) batteries have been regarded as an important candidate for next-generation energy storage devices due to their low cost and high theoretical energy density. However, several factors retard the practical use of Li-S batteries including the slow kinetics of lithium polysulfide (LiPS) transformation as well as the shuttle effect induced by the diffusion of LiPS that damages the cycling stability of Li-S batteries. In this study, a yolk@shell structured MnS@nitrogen-doped carbon (MnS@N-C) is developed as the S host and polysulfide conversion booster, which offers both the physical confinement of S species and accelerated kinetics toward LiPS catalytic conversion. As a result, the developed S/yolk@shell MnS@N-C delivers a higher rate performance compared to S/yolk@shell MnO@N-C and S/N-C and long cycle life with a remaining capacity of 636.1 mAh g–1 after 330 cycles at 0.5C. When equipped with MnS@N-C functional separators, S/yolk@shell MnS@N-C retains a capacity of 504.2 mAh g–1 after 1000 cycles at 1C. In addition, S/yolk@shell MnS@N-C also delivers a decent capacity decay of 0.16% per cycle after 300 cycles at 0.5C in a room-temperature Na-S battery.