Intrinsic activity regulation of metal chalcogenide electrocatalysts for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have been recognized as potential candidates for next-generation high-energy storage devices because of their high energy density, abundant sulfur reserves, and environmental friendliness. However, the development of Li-S batteries are still limited by sluggish sulfur redox kinetics and severe shuttle effect of soluble polysulfides. These challenges have been addressed by introducing metal chalcogenide (MC) electrocatalysts. This review first introduces the electrocatalytic mechanism for sulfur reduction/evolution reactions. Then, modulation strategies of the intrinsic activity of MCs including atomic vacancy, heteroatom doping, polynary engineering, heterostructure engineering, and synergy regulation are highlighted and summarized. Finally, future opportunities toward MC electrocatalysts in Li-S batteries are presented, with the aim to offer a fundamental understanding of the catalytic mechanism for sulfur redox reactions, and to provide some inspiration for rational design of electrocatalysts for high-energy and long-life Li-S batteries.