Control of the LiFePO4 electrochemical properties via a pray-drying-assisted a solid-phase reaction route using Fe3(PO4)2 as iron precursor

Abstract

Fe3(PO4)2 as iron precursor was prepared by liquid phase method with FeSO4 as iron source, and then LiFePO4(LFP) was made by high-temperature solid state reaction. The adjustment of Fe and P content is beneficial to the precise control of Fe3(PO4)2 precursor components and ensure the excellent electrochemical performance of LiFePO4 materials. It is shown that pH is very critical to the contents of iron and phosphorus in Fe3(PO4)2, and a stoichiometric ratio of high-yield Fe3(PO4)2 can be obtained at a pH of six. After Fe3(PO4)2 is mixed with Li3PO4 and glucose, high-energy ball milling and spray-drying technology are used to thoroughly mix the mixtures and control their morphology of them. The as-prepared LiFePO4 maintains the microporous spherical morphology by high-temperature solid-state method, which is formed in spray drying. At 700 °C, the LFP/C material has reaching 156, 147, 137, 128, 111, 96 mAh g−1 at 0.2 C, 0.5 C, 1 C, 5 C and 10 C rate, respectively, and after 500 long loops for 5 C, the capacity retention still maintains 49%. LFP prepared with ferrous iron phosphate as precursor has good cycling performance.