High performance FeF_x/C composites as cathode materials for lithium-ion batteries

FeF_x precursors were synthesized by a simplified one-step hydrothermal synthesis route with commercial Fe(OH)₃ and HF as raw materials; then the as-prepared precursor was calcined in different temperature and obtained FeF₃, FeF₂, and amorphous mixture FeF ₃-FeF₂. These materials were characterized by X-ray diffraction, scanning electron microscope, and X-ray photoelectron spectroscopy and used as cathode materials for lithium-ion batteries. The electrochemical tests show that the initial discharge capacities of FeF₃, FeF ₂, and amorphous mixture FeF₃-FeF₂ are as high as 204.6 mAh/g, 162 mAh/g, and 208.6 mAh/g, respectively, at the rate of 0.1 C in the range 2.0-4.5 V at 25 °C, and display very excellent discharge capacity retention rate after the first discharge process. Furthermore, the cyclic voltammogram test was used to illustrate the reaction mechanisms of the nanocomposites.