Controlled Formation of Mixed Nanoscale Domains of High Capacity Fe2O3-FeF3 Conversion compounds by Direct Fluorination

Abstract

A novel direct fluorination method under fluorine gas atmosphere with fluidized bed reactor (FBR) was proposed to convert nano-Fe2O3 to iron oxyfluoride/fluoride. No form of FeOF was verified after fluorinations at different temperatures. At initial lower fluorination temperature (<250 °C), mainly surface fluorination happened to the sample and gives the composition of Fe2O3-xF2x (x < 1). At the final fluorination temperature of 275 °C, porous interconnected nano domains of FeF3 and Fe2O3 are formed and coexisted within the same particle, which greatly improve the electrochemical performance of the sample.