Uniform loading of ultrathin MoS2 nanosheets on hollow carbon spheres with mesoporous walls as efficient sulfur hosts for promising lithium-sulfur batteries

Abstract

The electrochemical performance of lithium-sulfur batteries (LSBs) can be improved by combining rational structural design with the high-efficient catalyst to construct sulfur host materials. The PVP-assisted hydrothermal method was used to synthesize a composite (HCSM@uMoS2) with ultrathin MoS2 nanosheets uniformly loaded on hollow carbon spheres with mesoporous walls (HCSM). The ultrathin MoS2 nanosheets containing 1T metal phase (uMoS2) improved the electrical conductivity of the material while exposing more active sites, enhanced the adsorption to polysulfide and improved the redox reaction kinetics for polysulfide, thus fully suppressing the shuttle effect. Together with the advantages of HCSM, the mesoporous walls and internal cavity can offer enough sulfur storage room and significantly buffer the volume expansion of sulfur species; the high specific surface area and abundant porosity favor electron/ion transfers. As a result, the HCSM@uMoS2-S electrode exhibited outstanding electrochemical performance (675.4 mAh g−1 retention capacity at 0.5 C for 500 cycles) even under the conditions of high areal sulfur loading (5.6 mg cm−2) and less electrolyte (E/S = 10 μL mg−1). This study provides a reference for building sulfur hosts for high-capacity, long-life, and practical LSBs.