A review on the use of carbonate-based electrolytes in Li-S batteries: A comprehensive approach enabling solid-solid direct conversion reaction

Li-S batteries have attracted great attention from academia and industry because of their high theoretical capacity and energy density, arising from the multi-electron electrochemical reactions. Although significant progress has been made to improve the capacity and cycle life of these batteries, a major challenge has been overlooked. Ether-based electrolytes, commonly used in Li-S batteries, are highly volatile and impractical for many applications. On the other hand, carbonate-based electrolytes have been used in commercial Li-ion batteries for three decades and are a natural and practical choice to replace ether-based electrolytes in Li-S batteries. The lack of attention towards the use of carbonate-based electrolytes in Li-S batteries, is in part from the irreversible reaction between carbonate solvents and polysulfides anion that results in battery shut down, when conventional material designs and strategies are employed. Here, a comprehensive and critical review of recent progress on the use of carbonate-based electrolyte is presented. Throughout this work, we provide our insight to different approaches that can mitigate the irreversible reaction between carbonate solvents and sulfur cathode. First, we introduce the solid-solid direct conversion reaction of sulfur, which enables the successful use of carbonate electrolytes in Li-S batteries. Then, we discuss the progress made on design of cathodes, engineering of electrolytes, and strategies for Li metal protection, when carbonate electrolytes are used in Li-S batteries. Furthermore, the future directions to achieve a long-term cycling Li-S battery with carbonate electrolytes is provided. We believe that this work can be a useful source to draw the attention of Li-S battery field to develop practical Li-S batteries.