Fast Reaction Kinetics via Interfacial Mediation in Quasi- and All-Solid-State Lithium-Sulfur Batteries.

In recent years, lithium-sulfur batteries have attracted much interest owing to the natural abundance of sulfur and its high theoretical specific capacity (q _th ≈ 1,672 mAh g^-1), offering the potential to achieve cell-level energy densities exceeding 400 Wh kg^-1. While excess electrolyte facilitates redox reactions, it compromises specific energy and safety, driving the shift toward lean-electrolyte and solid-state systems. Although this helps suppress polysulfide shuttling, such strategies suffer from sluggish solid-solid conversion reactions and poor interfacial kinetics. Recently, studies adopting interfacial mediator strategies have emerged to address these challenges by enabling localized redox reactions at otherwise inactive interfaces. This perspective highlights advances in mediator-facilitated sulfur conversion under quasi- and all-solid-state conditions, offering insights into designing high-performance (electrolyte-efficient) lithium-sulfur batteries.