Metals and Alloys as Catalytic Hosts of Sulfur Cathode for Lithium-Sulfur Batteries

Lithium-sulfur batteries are recognized as one of the most promising next-generation energy storage devices, owing to the high theoretical energy density of 2600 Wh·kg^–1. However, their application has been seriously hindered by the sluggish electrochemical reaction kinetics of elemental sulfur and discharged products (Li₂S₂/Li₂S), and the notorious “shuttle effect” of soluble intermediate lithium polysulfide species, leading to poor cycle stability, low sulfur utilization and inferior coulombic efficiency. Introducing catalytic hosts into sulfur cathode is an efficient path to propel the conversion of sulfur-contained species, thus preventing the dissolution and loss of active-sulfur material in lithium-sulfur batteries. In this review, we summarize recent progresses on the uses of metals and alloys as the core catalytic host of sulfur, and demonstrate the catalytic mechanism in the conversion process of sulfur species with the help of metal and alloy hosts. Finally, future outlooks are proposed on the construction of catalytic hosts and the development of high-energy lithium-sulfur batteries.