Structure and Electrochemistry of Carbon-Metal Fluoride Nanocomposites Fabricated by Solid-State Redox Conversion Reaction

Utilizing a solid-state redox-driven conversion reaction enabled by mechanochemistry, conductive C:FeF 3 nanocomposites were fabricated from insulative CF 1 :FeF 2 precursors. All reactions were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The latter provided insights to the progression of the CF and C phases and the metal fluoride during the course of the reaction. Such nanocomposites resulted in a four order of magnitude increase in electrical conductivity and enabled excellent specific capacity approaching 500 mAh/g vs. Li with good reversibility, although at slow rates. Utilizing the theoretical basis of the technique, other couples were examined to experimentally isolate the oxidative power of CF 1 . In the process, we have also shown that a composite of CF 1 :CrF 2 can be easily converted to C:CrF 3 . The resulting nanocomposite exhibited a specific capacity of 682 mAh/g at an average voltage of approximately 1.9 V. The technique is also a powerful method for the fabrication of single phase metal fluoride solid solutions, as demonstrated with the fabrication of Cr 0 . 5 Fe 0 . 5 F 3 .