Carbon confinement synthesis of interlayer-expanded and sulfur-enriched MoS2+x nanocoating on hollow carbon spheres for advanced Li-S batteries

Abstract

High energy density and low-cost lithium-sulfur batteries have been considered as one of the most promising candidates for next-generation energy storage systems. However, the intrinsic problems of the sulfur cathode severely restrict their further practical application. Here, a unique double-shell architecture composed of hollow carbon spheres@interlayer-expanded and sulfur-enriched MoS2+x nanocoating composite has been developed as an efficient sulfur host. A uniform precursor coating derived from heteropolyanions-induced polymerization of pyrrole leads to space confinement effect during the in-situ sulfurization process, which generates the interlayer-expanded and sulfur-enriched MoS2+x nanosheets on amorphous carbon hollow spheres. This new sulfur host possesses multifarious merits including sufficient voids for loading sulfur active materials, high electronic conductivity, and fast lithium-ion diffusive pathways. In addition, additional active edge sites of MoS2+x accompanied by the nitrogen-doped carbon species endow the sulfur host with immobilizing and catalyzing effects on the soluble polysulfide species, dramatically accelerating their conversion kinetics and re-utilization. The detailed defect-induced interface catalytic reaction mechanism is firstly proposed. As expected, the delicately-designed sulfur host exhibits an outstanding initial discharge capacity of 1,249 mAh·g−1 at 0.2 C and a desirable rate performance (593 mAh·g−1 at 5.0 C), implying its great prospects in achieving superior electrochemical performances for advanced lithium sulfur batteries.