Towards the high energy density batteries via fluoride ions shuttling in liquid electrolytes: A review

Fluorine, as the most electronegative element, provides the highest electrode potential when it undergoes redox reactions. Moreover, fluoride ion is intrinsically an excellent charge carrier in both electrolytes and electrode structures owing to its small size, low atomic weight, and good ionic mobility. Hence, batteries based on fluorine electrochemistry, the so-called fluoride ion batteries (FIBs), have recently been deemed as an alternative next-generation high energy density battery system. This article reviews the recent progress in FIBs based on liquid electrolytes. The mechanisms, advantages, and drawbacks of FIBs are discussed. In the end, the perspective illuminating the research directions for further development is presented.