Optimizing Redox Reactions in Aprotic Lithium–Sulfur Batteries

Abstract The lithium–sulfur battery is regarded as one of the promising energy‐storage devices beyond lithium‐ion battery due to its overwhelming energy density. The aprotic Li–S electrochemistry is hampered by issues arising from the complex solid–liquid–solid conversion process. Recently, tremendous efforts have been made to optimize the electrochemical reaction in Li–S batteries through rationally designing compositions and structures of cathodes. However, a deep and comprehensive understanding of the actual mechanisms of Li–S batteries and their impact on the performance is still insufficient. The vigorous development of various electrochemical analysis and in situ techniques establish a bridge between the microstructure of components and the macroscopic electrochemical performance, thus providing more scientific guidance for the optimal design of Li–S batteries. In this review, based on insights into the mechanism of aprotic Li–S electrochemistry with the aid of in situ characterization and electrochemical methods, the advanced innovations in optimizing Li–S batteries are systematically summarized, including the materials design, cathode configurations optimization, and electrolyte engineering, with the aim to gain a comprehensive understanding of cathodic redox processes and thus achieve high‐performance Li–S batteries. The current status and possible future directions of the field are accordingly outlined.