Recent progress in ionic liquid-based electrolytes for nonaqueous and aqueous metal batteries

Nonaqueous Li metal batteries (LMBs) and aqueous Zn metal batteries (ZMBs) are promising next-generation secondary batteries owing to their high energy density. Selecting an appropriate electrolyte is critical for addressing the safety issues nonaqueous and aqueous metal batteries can encounter. Ionic liquids (ILs) have been widely used in secondary metal batteries because they are non-flammable, present good thermal stability, and have wide electrochemical windows. This review highlights the research progress on IL-based electrolytes for stable Li/Zn metal anodes. We focus particularly on these electrolytes' electrochemistry and functionalities at the electrolyte/anode interface for inhibiting dendrite growth, preventing side reactions, and enhancing electrochemical performance. It is expected that this review will shed some light on the development of ILs for next-generation metal batteries.