Rational design of ultrathin Mo2C/C nanosheets decorated on mesoporous hollow carbon spheres as a multifunctional sulfur host for advanced Li-S batteries

Abstract

Developing sulfur hosts with reasonable structure and effective catalyst is essential for lithium-sulfur (Li-S) batteries. Herein, a novel multifunctional sulfur host composed of hollow carbon spheres with mesoporous channels (MHCS) coupled with few ultrathin Mo2C/C nanosheets embedded with Mo2C nanocrystals ([email protected]2C/C) has been prepared via one-pot self-assembly and in-situ grown strategies. The Mo2C/C nanosheets with heterostructure can shorten the electron/ion transport path, and ultra-small Mo2C nanocrystals with abundant active sites contribute to enhancing chemical adsorption towards polysulfides and propel their conversion. Meanwhile, the MHCS facilitates physical adsorption towards polysulfides, effective sulfur/electrolyte permeation, fast electron/ion transportation, and sufficient buffering for volume change. Given these, the multifunctional [email protected]2C/C-S cathode demonstrates an initial specific capacity of 1316.8 mAh g−1 at 0.1 C and outstanding cycling stability with an average capacity decay rate of 0.045 % for 500 cycles at 0.5 C. Moreover, [email protected]2C/C-S cathode with high areal sulfur loading of 4.5 mg cm−2 can deliver a high initial discharge specific capacity of 797.4 mAh g−1, and a reversible capacity of 542.7 mAh g−1 after 500 cycles at 0.5 C. It is expected this work could provide a new perspective to the rational design of sulfur hosts for Li-S batteries with enhanced performance.