Cu–Pb Nanocomposite Cathode Material toward Room-Temperature Cycling for All-Solid-State Fluoride-Ion Batteries

All-solid-state fluoride-ion batteries (FIBs) are regarded as attractive alternatives to traditional energy storage systems because of their high energy density; however, they are not applicable at room temperature owing to sluggish ion transport in both the electrolyte and electrode. In this study, a rational design of a Cu–Pb nanocomposite is reported, which was tested as a room-temperature cathode material for all-solid-state FIBs. Following electrochemical pretreatment, self-generated PbF2 could act as a fast fluoride-ion conductor and consequently enhance the kinetics of the Cu/CuF2 phase transition process upon cycling. The detailed reaction mechanism and phase transition process were verified using the X-ray absorption near edge structure. The Cu–Pb nanocomposite could realize reversible (de)fluorination at room temperature with high performance and good cyclability.