Toward Practical Fluoride-Ion Batteries: A Review and Perspective on Liquid Electrolyte Development

Fluoride-ion batteries (FIBs) offer a promising alternative to lithium-ion batteries, due to their potential for higher energy density, lower cost, and abundant elemental resources. However, practical room-temperature FIBs are dependent on the development of advanced liquid electrolytes. This Perspective reviews the current state of liquid electrolytes for FIBs, examining both aprotic and protic solvent-based systems and their respective strengths and weaknesses. We discuss the key challenges in optimizing electrolyte properties, including achieving high salt solubility, expanding the electrochemical stability window, and enhancing chemical stability, all of which are essential for realizing practical FIBs. Building upon this analysis, we suggest future research directions in liquid electrolyte designs to overcome these challenges and ultimately enable the widespread adoption of fluoride-ion batteries for diverse energy storage applications.