Fast and Low Cost Synthesis of LiFePO[sub 4] Using Fe[sup 3+] Precursor

Submicrometer and phase-pure LiFePO 4 was prepared by carbothermal reduction of Fe 2 O 3 using a preliminary mechanical activation. The reaction mechanism, particle size, and electrochemical performance of as-prepared LiFePO 4 were studied and compared with LiFePO 4 obtained from the Fe 2 + precursor ( FeC 2 O 4 ⋅ 2 H 2 O ) using thermal analysis, X-ray diffraction, Mössbauer spectroscopy, scanning electron microscopy, and galvanostatic cycling. The carbothermal synthesis of LiFePO 4 from Fe 2 O 3 in inert atmosphere is a multistep process, including first the formation of Li – Fe 3 + phosphates, mainly pyrophosphate LiFeP 2 O 7 . A single-phase high crystalline LiFePO 4 is formed at temperatures ≥ 700 ° C . The preliminary mechanical activation accelerates the reaction due to a very fine grinding and an intimate mixing of the reactants. The specific discharge capacity of LiFePO 4 prepared from iron oxide is comparable with that of LiFePO 4 prepared from iron oxalate ( ∼ 155 mAh / g ) .