Enhanced Electrochemical Properties of LiFePO4 as Positive Electrode of Li-Ion Batteries for HEV Application

LiFePO4 materials synthesized using FePO4(H2O)2 and Li2CO3 blend were optimized in view of their use as positive electrodes in Li-ion batteries for hybrid electric vehicles. A strict control of the structural properties was made by the combination of X-ray diffraction, FT-infrared spectroscopy and magnetometry. The impact of the ferromagnetic clusters (γ-Fe2O3 or Fe2P) on the electrochemical response was examined. The electrochemical performances of the optimized LiFePO4 powders investigated at 60 ̊C are excellent in terms of capacity retention (153 mAh·g at 2C) as well as in terms of cycling life. No iron dissolution was observed after 200 charge-discharge cycles at 60 ̊C for cells containing Li foil, Li4Ti5O12, or graphite as negative electrodes.