Rationalizing Electrocatalysis of Li–S Chemistry by Mediator Design: Progress and Prospects

The lithium–sulfur (Li–S) battery is regarded as a next-generation energy storage system due to its conspicuous merits in high theoretical capacity (1672 mAh g⁻¹), overwhelming energy density (2600 Wh kg⁻¹), and the cost-effectiveness of sulfur. However, the practical application of Li–S batteries is still handicapped by a multitude of key challenges, mainly pertaining to fatal lithium polysulfide (LiPS) shuttling and sluggish sulfur redox kinetics. In this respect, rationalizing electrocatalytic processes in Li–S chemistry to synergize the entrapment and conversion of LiPSs is of paramount significance. This review summarizes recent progress and well-developed strategies of the mediator design toward promoted Li–S chemistry. The current advances, existing challenges, and future directions are accordingly highlighted, aiming at providing in-depth understanding of the sulfur reaction mechanism and guiding the rational mediator design to realize high-energy and long-life Li–S batteries.