Recent Advance in Ionic-Liquid-Based Electrolytes for Rechargeable Metal-Ion Batteries

From basic research to industry process, battery energy storage systems have played a great role in the informatization, mobility, and intellectualization of modern human society. Some potential systems such as Li, Na, K, Mg, Zn, and Al secondary batteries have attracted much attention to maintain social progress and sustainable development. As one of the components in batteries, electrolytes play an important role in the upgrade and breakthrough of battery technology. Since room-temperature ionic liquids (ILs) feature high conductivity, nonflammability, nonvolatility, high thermal stability, and wide electrochemical window, they have been widely applied in various battery systems and show great potential in improving battery stability, kinetics performance, energy density, service life, and safety. Thus, it is a right time to summarize these progresses. In this review, the composition and classification of various ILs and their recent applications as electrolytes in diverse metal-ion batteries (Li, Na, K, Mg, Zn, Al) are outlined to enhance the battery performances.