Preparation of MoS2/WS2 nanosheets by liquid phase exfoliation with assistance of epigallocatechin gallate and study as an additive for high-performance lithium-sulfur batteries.

The two-dimensional transition metal dichalcogenides have wide application value in many fields. Herein, MoS 2 and WS 2 nanosheets are produced by liquid phase exfoliation method assisted by epigallocatechin gallate. The effects of epigallocatechin gallate concentration and stripping time are investigated by UV–vis. The morphology and structure characterization of exfoliated nanosheets are studied by XRD, Raman, SEM, HRTEM and AFM, the results showing that the nanosheets have few layers and the exfoliated solution is homogeneous dispersion and stable. The exfoliated nanosheets produced by 2 mg ml−1 epigallocatechin gallate solution for 12 h have five monolayers approximately, presenting a phase transformation from 2H to 1T structure of MoS 2 nanosheets. Then, Graphene aerogel composites are prepared with the exfoliated MoS 2 /WS 2 nanosheets, which loaded sulfur and employed as the cathode of Li-S batteries. TEM results reveal that MoS 2 /WS 2 nanosheets are embedded in reduced graphene oxide, and sulfur is evenly distributed in the composites. The composites containing MoS 2 /WS 2 nanosheets achieve outstanding electrochemical performance, during to the polysulfide adsorption capability of MoS 2 /WS 2 nanosheets and reducing the shuttle effect in Li-S batteries. It demonstrates a good application of exfoliated MoS 2 /WS 2 nanosheets in Li-S batteries. [ABSTRACT FROM AUTHOR]