Function-Oriented Electrolyte Additives: Chemical Strategy to Enhance the Performance of Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have emerged as a promising candidate for next-generation energy storage systems. However, the practical application of Li-S batteries faces several significant technical challenges, such as the "shuttle effect," sluggish polysulfide conversion kinetics, irreversible loss of active materials, and disordered growth of lithium dendrites on the anode. To overcome these issues, the strategic incorporation of functional electrolyte additives has emerged as a novel approach for enhancing Li-S battery performance. This paper focuses on reviewing functional electrolyte additives with different properties and their action mechanisms. First, based on the structure and composition of additive molecules, they are classified into inorganic molecules, organic molecules, ionic liquids, and polymer-based additives. Then, the effects of additives on sulfur cathodes are deeply expounded from aspects such as sulfur fixation, construction of interfacial CEI layers, alteration of sulfur redox pathways, and realization of 3D deposition of Li₂S. Furthermore, the construction of SEI layers on lithium metal anodes, lithium ion migration, and inhibition of lithium dendrites by additives are summarized and compared. Finally, the future development of electrolyte additives for Li-S batteries is projected, offering theoretical insights and technological strategies for the development of a highly stable Li-S battery.