Recent advances in electrolyte design for optimized lithium polysulfides solvation in lithium-sulfur batteries

Lithium–sulfur (Li-S) batteries have emerged as a promising candidate for next-generation secondary batteries due to their high energy density and cost-effective sulfur cathodes. These batteries operate through electrochemical reactions involving sulfur, during which lithium polysulfides (LiPSs) are formed as liquid-phase intermediates. The solvation behavior of LiPSs plays a crucial role in determining the electrochemical performance and cycling stability of Li-S batteries. Electrolytes, as a key factor, govern the dissolution of LiPSs, with the properties, quantities, and ratios of components playing a critical role in forming the solvation structure of both Li⁺ ions and LiPSs. In this review, the extent of LiPS solvation is systematically categorized into highly, sparingly and weakly solvating electrolytes, and the influence of solubility on electrochemical performance is elucidated. Furthermore, the effects of additives and diluents on the solvation structures of LiPSs are analyzed to reveal the underlying mechanisms that govern their electrochemical behavior. This review emphasizes the importance of optimizing LiPS solvation properties through rational electrolyte design to enhance the performance and stability of Li-S batteries, providing valuable insights into the development of advanced electrolyte systems.