Synergetic Anion Vacancies and Dense Heterointerfaces into Bimetal Chalcogenide Nanosheet Arrays for Boosting Electrocatalysis Sulfur Conversion.

Abstract

Vacancy and interface engineering are regarded as effective strategies to modulate the electronic structure and enhance the activity of metal chalcogenides. However, the practical application of metal chalcogenides in lithium-sulfur (Li-S) batteries is limited by their low conductivity, rapid decline in catalytic activity, and large volume variation during the discharging/charging process. Herein, bimetal sulfide (CoZn-S) nanosheet arrays with sulfur vacancies and dense heterointerfaces are proposed to accelerate sulfur conversion and improve the performance of Li-S batteries. Systematic investigations reveal that sulfur-vacancy and build-in interfacial field in CoZn-S facilitate the electron transfer and regulate the electronic structure. The well-designed 3D nanosheet array structures shorten the ion-transport pathway and inhibit the volume fluctuation of CoZn-S during the electrocatalysis process. Density functional theory studies confirm that the built-in interfacial field and sulfur vacancy can promote the thermodynamic formation and decomposition of Li₂ S, thus improving their intrinsic activity.