PEO-Linked MoS₂-Graphene Nanocomposites with 2D Polar-Nonpolar Amphoteric Surfaces as Sulfur Hosts for High-Performance Li-S Batteries

Layered MoS₂-graphene nanocomposites with 2D polar-nonpolar amphoteric surfaces, which were used to confine sulfur for Li-S batteries, have been successfully fabricated through the assembly of polar MoS₂ layers and nonopolar graphene with poly(ethylene oxide) cross-linking. Benefiting from the high conductivity of graphene and the strong chemical bonding between polar MoS₂ and polysulfides, the MoS₂-graphene composites not only ensure unimpeded electrical conducting to the insulating sulfur but also effectively entrap polysulfides therein. The ex situ study further reveals that the MoS₂-graphene composites enable spatially regulated Li₂S deposition by the preferential deposition of solid Li₂S product onto the polar MoS₂ layers, making a large amount of fast electron transport paths exposed on graphene for further sulfur reduction. Therefore, the obtained MoS₂-sulfur-graphene nanocomposites present excellent rate performance and cycling stability with high reversible capacities of 895 mA h g^-1 at 0.2 C after 100 cycles and 524 mA h g^-1 at 1 C after 200 cycles. These encouraging results suggest that the layer-structured sulfur cathode materials through the rational integration of 2D polar and nonpolar amphoteric surfaces would be a promising strategy for enhancing the electrochemical performances of advanced Li-S batteries.