A ferrocene-based carbon–iron lithium fluoride nanocomposite as a stable electrode material in lithium batteries

A nanocomposite comprising carbon–iron LiF was prepared by pyrolysis of a mixture of ferrocene and LiF at 700 °C under an argon atmosphere for 2 h. The structure and morphology of the material was characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), BET analysis, and Mössbauer spectroscopy. The composite consists of multi-walled carbon nanotubes and onion-type graphite structures in which Fe and Fe3C nanoparticles are encapsulated, and LiF is dispersed within the carbon matrix. The sample contains both micro- (0.025 cm3 g−1) and mesopores (0.14 cm3 g−1), and has a total specific surface area of 82 m2 g−1. Its charge/discharge performances were studied in the potential range 0.5 V to 4.3 V at a current density of 20.83 mA g−1 at 25 °C. It exhibited an initial discharge capacity of 324 mAh g−1 with respect to the active mass of FeF3. After five cycles the capacity reached 280 mAh g−1 and is maintained at about 270 mAh g−1 over 200 cycles. A reversible specific capacity of about 170 mAh g−1 was realized when the potential range was between 1.3 and 4.3 V.