Synthesis and Electrochemical Performances of Nano-particle FePO4 and Ce-doped FePO4 Cathode Materials for Lithium Ion Batteries by Microemulsion Method

Nano-sized FePO4 and Fe1-xCexPO4 (x=0.02, 0.04, 0.08) cathode materials were synthesized by microemulsion method. The samples were prepared via a microemulsion system in a H2O/cyclohexane/Triton x-100/n-butyl alcohol at different temperatures (30 degrees C, 45 degrees C, 50 degrees C, 60 degrees C) and then sintered at 380 degrees Cand 460 degrees C for 3 h. The thermal stability, structure and morphology were investigated by means of TG/DCS, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and the electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic charge and discharge tests. Results show that synthesis temperature has a great influence on the performances of FePO4, and the sample synthesized at 45 degrees C shows the best performances with a diameter of about 20 nm and a high discharge initial specific capacity of 142mAh/g and retaining 123mAh/g after 20 cycles at 0.1 C. The Ce-doped FePO4, Fe1-xCexPO4 (x=0.02, 0.04, 0.08), can effectively improve the electrochemical properties of FePO4 cathode materials. The Fe0.96Ce0.04PO4 exhibits an initial discharge capacity of 158.2mAh/g and retains 152mAh/g after 20 cycles at 0.1 C. Hence, Fe0.96Ce0.04PO4 is a promising candidate for cathode materials of lithium ion batteries.