P.F. Lu, H.D. Shia, J.Q. Qin, Z.-S. Wu*

FlatChem, 2020, 24, 100209.

DOI: 10.1016/j.flatc.2020.100209 [PDF]

Lithium-sulfur (Li-S) batteries have proven their merits for promising high-energy-density batteries. However, the notorious shuttling of polysulfides severely hinders their widespread applications. Herein, we report an efficient polysulfide double-blocking strategy that simultaneously employs the in-situ formed sulfur encapsulated in porous carbon materials (S@C) as cathode and metal-organic framework-derived CoS₂nanosheets as polar interlayer to fabricate highly-stable Li-S batteries. The S particles with high loading of 71% are uniformly confined within the large voids and cavities of porous carbon skeleton, and the carbon shell could control the cathodic volume, ensure the fast ionic transfer, and physically confine the polysulfides. Further, the nanosheet-like CoS₂interlayer presents strong chemical adsorption of polysulfides, as confirmed by the experiments and DFT calculations. As a result, the strong synergistic effect of S@C cathode and CoS₂interlayer yields superior Li-S batteries with high initial capacity (1271 mAh g⁻¹at 0.5C), remarkably enhanced rate capability and excellent cyclability with a quite low fading rate of 0.136% per cycle. Therefore, our proposed strategy of double blocking polysulfides will offer new ways for achieving high-stable and long-lifetime Li-S batteries.