Fluorine-Free Strategies for Sustainable Batteries.

Fluorinated compounds support several essential functions in rechargeable batteries, including salt dissociation, interphase formation, voltage stabilization, and electrode cohesion. Their extensive use, however, is accompanied by hydrolytic instability, corrosive decomposition products, persistent fluorinated residues, and difficulties in electrode recycling. This review evaluates strategies for reducing or eliminating intentionally introduced fluorine in electrolyte and binder systems for lithium- and sodium-based batteries. Fully fluorine-free formulations are distinguished from fluorine-reduced systems, and representative salts, solvents, additives, solid/quasisolid electrolytes, and aqueous binders are compared in terms of ion transport, voltage tolerance, interfacial chemistry, safety, and practical applicability. Particular attention is paid to the tradeoff between interphase stability and impedance, as well as to the scalability and end-of-life compatibility of aqueous electrode processing. Finally, priorities are proposed for realistic full-cell evaluation and coordinated material, manufacturing, and recycling design.