A New Synthetic Route for Preparing LiFePO[sub 4] with Enhanced Electrochemical Performance

Abstract

Nanocrystalline LiFePO4LiFePO4 was obtained by heating amorphous nanosized LiFePO4.LiFePO4. The amorphous material was obtained by lithiation of FePO4FePO4 synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH4)2(SO4)2⋅6H2OFe(NH4)2(SO4)2⋅6H2O and NH4H2PO4,NH4H2PO4, using hydrogen peroxide as the oxidizing agent. The materials were characterized by chemical analysis, thermogravimetric and differential thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The Brunauer- Emmett-Teller method was used to evaluate the specific surface area. Nanocrystalline LiFePO4LiFePO4 showed very good electrochemical performance delivering about the full theoretical capacity (170 Ah kg−1)(170 Ah kg−1) when cycled at the C/10 rate. A capacity fade of about 0.25% per cycle affected the material upon cycling. © 2002 The Electrochemical Society. All rights reserved.