Heterostructures of MXene and Graphene as Cathode Hosts Improving Anchoring and Reaction Dynamics for Li–S Batteries

Abstract

Lithium–sulfur batteries have attracted great enthusiasm because of the high specific capacity and energy density, while the application is still limited by the “shuttle effect” of polysulfides and slow reaction dynamics. Here, different MXene-graphene heterostructures were used as sulfur cathode hosts, and the electrochemical performances were studied via first-principles simulation. Compared with a single MXene or graphene component, the MXene side of the heterostructure could more effectively anchor lithium polysulfides and inhibit the shuttle effect. However, more importantly, Ti₂CS₂-graphene heterostructures could more effectively promote the sulfur reduction reaction during the discharging process and reduce the diffusion barrier of Li⁺/decomposition barrier of Li₂S during the charging process, which is beneficial for improving the sluggish dynamics in Li–S batteries. This work suggests that Ti₂CS₂-graphene heterostructures could be used as potential cathode hosts and provide theoretical guidelines for the design of cathode hosts for Li–S batteries.