Electrochemical Properties of Cathode Material LiFePO4 with Ti Substitution

Ti substituted LiFePO4 with nominal composition Li1-4yTiyFePO4 (y = 0, 0.01, 0.02, 0.03, 0.04, and 0.05) cathode materials were prepared by solid-state reaction. The as-prepared samples were characterized by X-ray diffraction, X-ray absorption spectroscopy, cyclic charge-discharge, cyclic voltammograms, and electrochemical impendence spectroscopy. The X-ray diffraction results indicate that the increase of Ti4+ amount leads to the expansion of the LiFePO4 lattice monotonically, but the XAS reveals that small amount of doped Ti can also form TiO2-anatase impurities. At 0.1 C rate, doping of Ti causes a decrease in charge and discharge capacities. However, at higher C rate, the charge/discharge capacities are improved. Li0.96Ti0.01FePO4 exhibits the optimized electrochemical performance. (C) 2013 The Electrochemical Society.