Fast electrochemical kinetics and strong polysulfide adsorption by a highly oriented MoS2 nanosheet@N-doped carbon interlayer for lithium–sulfur batteries

Abstract

The polysulfide shuttle effect and sluggish reaction kinetics can severely reduce the sulfur utilization and cycle stability of Li–S batteries, undermining their use in practical applications. Herein, we design a core–shell nanocomposite by encapsulating radially oriented MoS₂ nanosheets by porous nitrogen-doped carbon (MoS₂@NC) via an eco-friendly method. The highly oriented MoS₂ nanosheets in MoS₂@NC avoid aggregation of the active sites for polysulfide adsorption, and the desirable integration of the catalytic MoS₂ nanosheet core and a highly conductive carbon shell provides a constant flow of electrons to the captured polysulfides for improved polysulfide conversion kinetics. The combined benefits of high polysulfide inhibition and smooth electron and Li⁺ transfer by a thin layer of MoS₂@NC (3.3 μm thick) enable a simple sulfur–carbon black cathode with high reversible capacities, good rate performances (876 mA h g⁻¹ at 3C), an excellent cycle stability over 1500 cycles with a negligible 0.034% decay per cycle, and satisfactory areal capacities with increased sulfur loading (2.0–3.7 mA h cm⁻² at various rates). This work provides a proof-of-concept study on the rational design of interlayer materials in energy storage systems.