High-capacity
metal oxide conversion
anodes for
lithium-ion batteries (LIBs) are primarily limited by their poor reversibility and cycling stability. In this study, a promising approach has been developed to improve the electrochemical performance of a
MoO2 anode by direct fluorination of the prelithiated
MoO2 . The fluorinated
anode contains a mixture of crystalline
MoO2 and amorphous
molybdenum oxyfluoride phases, as determined from a suite of characterization methods including X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, and scanning transmission electron microscopy. Electrochemical measurements indicate that fluorination facilitates the
conversion reaction kinetics, which leads to increased capacity, higher coulombic efficiency, and better cycling stability as compared to the nonfluorinated samples. These results suggest that fluorination after prelithiation not only favors formation of the
oxyfluoride phase but also improves the
lithium-ion diffusivity and reversibility of the
conversion reaction, making it an attractive approach to address the problems of conversion
electrodes. These findings provide a new route to design high-capacity negative
electrodes for LIBs.