Chloride-functionalized electrolyte design for safe and high-energy-density lithium metal batteries.

The development of lithium metal batteries (LMBs) has been hindered by the high cost and environmental issues associated with conventional fluorinated electrolytes, and regulatory concerns over perfluoro- and polyfluoroalkyl substances (PFAS) have accelerated the shift toward non-fluorine electrolyte systems as a sustainable alternative. As a result, chloride-functionalized electrolytes, taking advantage of the unique properties of chlorine atoms, have emerged as a promising alternative solution, featuring inherent flame retardancy, improved high-voltage stability and the formation of a LiF/LiCl hybrid interface conducive to kinetics. In this minireview, we systematically reviewed this paradigm shift, analyzing the molecular design, solvation structure regulation and interfacial engineering of chlorinated systems. We highlight their exceptional performance in high voltage, wide-temperature ranges, and long cycle operations, along with their evolution from functional additives to core electrolyte components. Our primary objectives are to provide a comprehensive and critical analysis of the structure-property relationships, performance advantages, and existing challenges in this field. This minireview aims to establish a foundational framework and identify future research directions for developing chlorinated electrolytes, ultimately guiding the design of safer and more sustainable LMBs.