Eutectic Electrolytes in Advanced Metal-Ion Batteries

Metal-ion batteries (MIBs) are promising for large-scale energy storage because they can alleviate the inherent intermittency of renewable energy. As an indispensable part of MIBs, electrolytes influence the electrochemical performance. Recently, the new concept of eutectic electrolytes has aroused extensive research attention in the field of MIBs due to their simple synthesis and eco-friendly features. Nevertheless, the development of eutectic electrolytes is still in its infancy and deserves further attention. This review focuses on the systematic understanding of the relationship between eutectic electrolytes and the corresponding performances of MIBs. First, fundamentals of eutectic electrolytes are described. Then, recent progress in the use of eutectic electrolytes in MIBs is introduced, including the correlations between structure and properties, the chemistry at the electrode interface, and the ion/charge transport mechanism. Finally, the challenges and prospects related to eutectic electrolytes are discussed. This Focus Review will provide better directions to devise advanced eutectic electrolytes for high-performance MIBs.