LAUSR

BiF3 is a strong candidate for a cathode material in fluoride shuttle batteries (FSBs), which utilize defluorination of metal fluorides and fluorination of metals. Much interest has been shown in FSBs as next-generation batteries with high energy densities. Elucidation and control of reactivity and mechanisms in FSB reactions are crucial for the development of FSBs with high performances. In the present work, structural transformation, reactivities, and mechanisms in FSB reactions of BiF3 microparticles partly embedded in a gold plating film (BiF3/gold, mainly orthorhombic BiF3 (o-BiF3) containing small amounts of cubic BiF3 (c-BiF3)) were studied by in-situ Raman microscopy. Reactivities and mechanisms in defluorination were found to be different for o-BiF3 and c-BiF3. In an ionic-liquid-based electrolyte, gradual transformation of o-BiF3 into cubic c-BiF3 occurred. When the voltage of BiF3/gold (cathode) vs a Pb counter electrode (anode) was decreased from OCV (0.7 V) to 0.05 V step by step, direct defl...