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

FeFx 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 FeF3-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, FeF2, 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 degrees 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. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798423]