MoS2 quantum dot-decorated CNT networks as a sulfur host for enhanced electrochemical kinetics in advanced lithium–sulfur batteries

Abstract

The slow redox kinetics and shuttle effect of polysulfides severely obstruct the further development of lithium–sulfur (Li–S) batteries. Constructing sulfur host materials with high conductivity and catalytic capability is well acknowledged as an effective strategy for promoting polysulfide conversion. Herein, a well-designed MoS₂ QDs-CNTs/S@Ni(OH)₂ (labeled as MoS₂ QDs-CNTs/S@NH) cathode was synthesized via a hydrothermal process, in which conductive polar MoS₂ quantum dot-decorated carbon nanotube (CNT) networks coated with an ultrathin Ni(OH)₂ layer acted as an efficient electrocatalyst. MoS₂ QD nanoparticles with a high conductivity and catalytic nature can enhance the kinetics of polysulfide conversion, expedite Li₂S nucleation, and decrease the reaction energy barrier. The thin outer Ni(OH)₂ layer physically confines active sulfur and meanwhile provides abundant sites for adsorption and conversion of polysulfides. Benefiting from these merits, a battery using MoS₂ QDs-CNTs/S@NH as the sulfur host cathode exhibits excellent electrochemical performances with rate capabilities of 953.7 mA h g⁻¹ at 0.1C and 606.6 mA h g⁻¹ at 2.0C. A prominent cycling stability of a 0.052% decay rate per cycle after 800 cycles is achieved even at 2C.