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.