Nano storage-boxes constructed by the vertical growth of MoS2 on graphene for high-performance Li-S batteries

Abstract

In order to accelerate the reaction kinetics of lithium-sulfur batteries, the introduction of electro catalysis and proper structural control of the sulfur cathode is urgently needed. MoS2 nano sheets was selectively grown vertically (V-MoS2) on the microwave-reduced graphene (rGO) sheets through chemical coupling to construct a self-supporting sulfur cathode with a nano storage-box structure (V-MoS2 as the wall and rGO as the bottom). RGO, which has a high conductivity of 37 S cm−1, greatly accelerates the transfer of electrons from the active sites on the edge of the layer to the solution. The introduction of carbon tubes can connect the abundant pores in the foam and act as a long-range conductive path. The 2D-orthogonal-2D structure maximally exposes the edge active sites of MoS2, and together with graphene form a nano reactor of sulfur, intermediate lithium polysulfides and discharge product Li2S(2). The effective combination of the microstructure confinement of the nano storage-boxes and the efficient synchronous catalytic mechanism of V-MoS2 greatly improves the electrochemical performance of the lithium-sulfur batteries. As a result, the assembled lithium-sulfur battery displays a high initial discharge capacity of 1379 mAh g−1, good cycle stability (86% capacity retention after 500 cycles at 0.1C) and superior rate performance. © 2021 Science Press