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

Abstract

Layered MoS 2 –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 MoS 2 layers and nonopolar graphene with poly(ethylene oxide) cross-linking. Benefiting from the high conductivity of graphene and the strong chemical bonding between polar MoS 2 and polysulfides, the MoS 2 –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 MoS 2 –graphene composites enable spatially regulated Li 2 S deposition by the preferential deposition of solid Li 2 S product onto the polar MoS 2 layers, making a large amount of fast electron transport paths exposed on graphene for further sulfur reduction. Therefore, the obtained MoS 2 –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.