Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

Abstract Li‐ion batteries (LIBs) are the energy storage systems of choice for portable electronics and electric vehicles. Due to the growing deployment of energy storage solutions, LIBs are increasingly required to function safely and steadily over a broad range of operational conditions. However, the conventional electrolytes used in LIBs will malfunction when the temperatures fall below zero or elevate above 60 ° C. Further, conventional electrolytes are toxic and flammable, leading to severe safety risks, especially in the case of an accident or overheating. Therefore, an ever‐growing body of research has been dedicated to the development of electrolytes characterized by high ionic conductivity, excellent electrochemical stability, and operability over a wide temperature range. In this Progress Report, the optimization of liquid‐based electrolytes achieved by controlling Li salts, functional additives, and solvents is discussed first. Next, gel‐polymer and all‐solid‐state electrolytes (i.e., ceramics, polymers, and their composites) are presented. Examples of advanced batteries (Li/Na/Zn‐ion batteries and Li‐metal batteries) capable of working over a broad temperature window are highlighted. Morever, recent computational studies aimed at designing and understanding electrolytes are reviewed. Finally, challenges and perspectives regarding emerging electrolyte materials are proposed with the goal of triggering the further development of high‐performance, safe, and wide‐temperature‐operating electrolytes.