Eutectic electrolytes: a new platform for high-safety batteries

Abstract

Eutectic electrolytes (EEs) have garnered significant attention in the field of metal-ion batteries due to their remarkable properties, including high flame retardancy and excellent thermal and electrochemical stability. Beyond the intrinsic advantages of EEs, the potential of composite electrolytes formed by combining EEs with other electrolytes is emerging as a crucial area of research and development. This review begins by elucidating the components (metal salts, ligands and additives), formation mechanisms (hydrogen bonding, Lewis acid–base and van der Waals interactions), and the basic properties pertinent to EEs, which are presented through common characterization techniques and simulation calculations. Subsequently, it highlights the recent advancements in the application of both intrinsic EEs and the composites with other electrolyte systems, such as eutectic-aqueous electrolytes, eutectic-polymer electrolytes, and eutectic-inorganic solid electrolytes. Finally, the discussion addresses the challenges faced by EEs and offers perspectives on future research directions, aiming to provide a more informed pathway for the design of high-performance EEs suitable for large-scale energy storage applications.