Heterostructures of doped graphene and MoX2 (X = S and Se) as promising anchoring materials for lithium–sulfur batteries: a first-principles study

Abstract

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to their high theoretical energy density. However, the detrimental shuttle effect is a main obstacle that greatly hampers the wide commercial applications of Li–S batteries. Introducing suitable anchoring materials to immobilize soluble Li₂S_n species is an effective strategy to alleviate this challenge. Herein, by means of comprehensive density functional theory (DFT) computations, we theoretically designed a class of heterostructure as anchoring materials for Li–S batteries, which is composed of the stacking between a transition metal dichalcogenide (MoX₂, X = S and Se) monolayer and B- or N-doped graphene. We found that these heterostructures show outstanding anchoring performance for soluble Li₂S_n species due to the remarkable binding strength with a suitable range of binding energies from 1.20 to 2.05 eV induced by charge transfer, thus effectively anchoring the soluble Li₂S_n species to avoid their dissolution into electrolytes and save their structural intactness. In addition, the diffusion of Li atoms on the surface of these heterostructures exhibits a low energy barrier, facilitating the electrochemical process. Thus, these proposed heterostructures are a novel class of promising anchoring material for Li–S batteries.