Optimized LiFePO4 for lithium battery cathodes

LiFePO4 powders were synthesized under various conditions and the performance of the cathodes was evaluated using coin cells. The samples were characterized by X-ray diffraction, scanning electron microscope observations, Brunauer, Emmett, and Teller surface area measurements, particle-size distribution measurements, and Mossbauer spectroscopy. Ab initio calculation was used to confirm the experimental redox potentials and Mossbauer parameters. The choice of a moderate sintering temperature (500 degreesC < T < 600 degreesC) and a homogeneous precursor enabled nearly perfect utilization of >95% of the 170 mAh/g theoretical capacity at room temperature. There are two main obstacles to achieving optimum charge/discharge performance of LiFePO4: (i) undesirable particle growth at T > 600 degreesC and (ii) the presence of a noncrystalline residual Fe3+ phase at T < 500<degrees>C. (C) 2001. The Electrochemical Society. All rights reserved.