Two-Step Catalytic Against Polysulfide Shuttling to Enhance Redox Conversion for Advanced Lithium-Sulfur Batteries.

Abstract

The development of lithium-sulfur batteries is seriously hindered by the shuttle effect of lithium polysulfides (LiPSs) and the low electrical conductivity of sulfur. To solve these problems, efficient catalysts can be used to improve the conversion rate of LiPSs and the conductivity of sulfur cathode. Herein, annealed melamine foam supported MoSe2 (NCF@MoSe2) is used as interlayer and the MoSe2/MoP heterojunction obtained by phosphating MoSe2 is further used as the catalyst material for metal fusion with a sulfur element. The interlayer can not only improve the electrical conductivity and effectively adsorb and catalyze LiPSs, but more importantly, the MoSe2/MoP heterojunction can also effectively adsorb and catalyze LiPSs, so that the batteries have a dual inhibition shuttling effect strategy. Furthermore, the rapid anchor-diffusion transition of LiPSs, and the suppression of shuttling effects by catalyst materials are elucidated using theoretical calculations and in situ Raman spectroscopy. The two-step catalytic strategy exhibits a high reversibility of 983mAhg-1 after 200 cycles at 0.5C and a high-rate capacity of 889mAhg-1 at 5C. This work provides a feasible solution for the rational design of interlayer and heterojunction materials and is also conducive to the development of more advanced Li-S batteries.