Solidifying Cathode–Electrolyte Interface for Lithium–Sulfur Batteries

摘要

Lithium-sulfur (Li-S) batteries, with their distinct advantages in energy output, cost, and environmental benignancy, have been recognized as one of the most promising candidates for near-future energy storage markets. However, the energy storage technology based on Li-S systems, even at the single cell level, is far from commercialization. The implementation of the technology is hindered by unstable electrochemistry at the electrode-electrolyte interface, especially the cathode-electrolyte interface. In cases where the cathode builds a solid-liquid interface with the electrolyte, strong interactions between discharge intermediates of S and solvent molecules of the liquid electrolyte lead to continuous loss of active S species from the cathode to the anode through an electrochemical shuttle process, and hampers the cycling performance of the battery. By solidifying the cathode-liquid interface, the polysulfide-solvent interaction is expected to be alleviated and the Li-S electrochemistry improved. In this Progress Report, the strategies to build a solidified cathode-electrolyte interface in liquid, quasi-solid-state and all-solid-state Li-S systems are summarized, and the fundamentals of charge transfer and chemical evolutions at the interface are discussed. With these discussions, the rational interfacial design of Li-S batteries is elucidated, toward optimal storage performance and operational durability.