Characterization of two lithiation reactions starting with an amorphous FePO4 precursor

LiFePO4 was prepared using two synthetic routes which involved the precipitation and lithiation of an amorphous FePO4 precursor followed by a thermal treatment. Both hydrated and dehydrated FePO4 were used. The XRD patterns confirm the amorphous nature of both the precipitated and the lithiated product, while a crystalline LiFePO4 product is obtained after thermal treatment. Mössbauer spectroscopy was used to analyse the oxidation state of iron during various stages of the reaction. The Mössbauer data demonstrates a large amount of Fe3+ ions in the lithiated samples which suggest that the lithiation reaction does not go to completion. Therefore, the formation of LiFePO4 may be in part associated with the thermal treatment and not the lithiation step.