Electrolyte Additives for High‐Energy‐Density Lithium–Sulfur Batteries: From Fundamental Challenges to Rational Design Strategies

Lithium–sulfur (Li–S) batteries are regarded as one of the next‐generation batteries owing to high theoretical energy density and low cost. However, their practical application is severely hindered by lithium polysulfides (LiPSs) shuttle, which not only leads to sluggish sulfur redox kinetics at the cathode but also induces parasitic reactions at the anode. Functional electrolyte additives provide a versatile approach to simultaneously tailoring interfacial chemistry, modulating LiPSs conversion, stabilizing lithium (Li) anode, and improving electrolyte compatibility. Moreover, electrolyte additive engineering is increasingly recognized as a key enabler for the high‐energy‐density Li–S pouch cells. In this review, we comprehensively summarize the recent advances in electrolyte additives for Li–S batteries from interfacial regulation. We first discuss the working mechanisms of various additives in governing sulfur redox reactions, suppressing LiPSs shuttle, and stabilizing Li‐metal anodes. We then highlight recent progress in additives design for high‐energy‐density pouch cells, lean‐electrolyte and wide temperature. Additionally, we highlight advanced characterization techniques that provide mechanistic insights into interfacial evolution. Finally, we present perspectives on the rational design of electrolyte additives. This review aims to establish a comprehensive framework for electrolyte additives and provide general design principles that can be extended to other high‐energy rechargeable battery.