The influence of the Li + addition rate during the hydrothermal synthesis of LiFePO 4 on the average and local structure.

A hydrothermal method was used to synthesize LiFePO 4 to explore the effect of the rate of addition of the Li + precursor to a mixture of the Fe 2+ and PO 4 3- precursors. Both the average and local structures were investigated using powder X-ray diffraction, Mössbauer spectroscopy and X-ray absorption spectroscopy. Slower addition rates led to increased oxidation of Fe 2+ to Fe 3+ despite purging all solutions constantly, as well as increased defects. The local structure as determined by extended X-ray absorption fine structure displayed far less variation between the samples. The formation of a Li 3 PO 4 impurity appeared to be independent of the Li + addition rate.