Synthesis and Characterization of Amorphous Hydrated FePO[sub 4] and Its Electrode Performance in Lithium Batteries

Abstract

Amorphous iron(III) phosphate was synthesized by spontaneous precipitation from equimolar aqueous solutions of Fe(NH4)(2)(SO4)(2).6H(2)O and NH4H2PO4, using hydrogen peroxide as the oxidizing agent. The material was characterized by chemical analysis, thermogravimetrical analysis, differential thermoanalysis, X-ray powder diffraction, and scanning electron microscopy. The material was tested as a cathode in nonaqueous lithium cells. Galvanostatic intermittent titration technique was used to follow the lithium intercalation process. The effect of firing on the specific capacity was also tested. The material fired at 400degreesC showed the best electrochemical performance, delivering about 0.108 Ah g(-1) when cycled at C/10 rate. The capacity fade upon cycling was found as low as 0.075% per cycle. (C) 2002 The Electrochemical Society.