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.