Catalytic-conversion behavior of MoS2 for polysulfides by nickel introduction and phosphorous-doping in advanced lithium-sulfur batteries

Abstract

Lithium-sulfur batteries (LSBs) have aroused remarkable concern as promising energy storage equipments owing to the high theoretical capacity and energy density. Efficient conversion of lithium polysulfides into S as well as Li2S/Li2S2 in the charge and discharge process is a crucial factor to improve the performance of LSBs. Among all the competing polysulfides conversion catalysts, MoS2 is considered as the one of the strongest competitors. Herein, the dual effects of nickel introduction and phosphorus doping on the morphology, structure and electrochemical properties of MoS2 materials are detailedly investigated. It has been found that the Ni-P coordinated sites on the MoS2 can provide the affluent sites for adsorption and conversion of polysulfides. Meanwhile, the phase transition of MoS2 from 2H phase to metallic 1T phase can be distinctly improved owning to nickel introduction, which enhances the electrochemical performances of LSBs. Besides, the P0.1-Mo0.9Ni0.1S2/CNT/S displays a good initial capacity of 742 mAh g−1 with a low fading rate of 0.075% per cycle at 1C as well as the discharge capacity of 463 mAh g−1 at the 500th cycle. Therefore, the strategy of Ni introduction and heteroatom doping can effectively inhibit Polysulfides shuttle and promote the performance of LSBs.