Preparation of iron phosphate cathode material of Li3Fe2(PO4)3 by hydrothermal reaction and thermal decomposition processes

Well-crystallized Li3Fe2(PO4)3 with an orthorhombic β-Fe2(SO4)3-type structure was able to be synthesized by using two synthetic routes, where hydrothermal reaction and successive heat treatment with relatively low temperatures were employed. The samples prepared were found to show orthorhombic symmetry, contrary to the fact that a conventional solid state synthesis heating at temperatures higher than 1000 °C usually gives monoclinic symmetry. The sample showed two plateau potentials of 2.8 and 2.7 V vs. Li/Li+ upon discharge, and the total discharge capacity of the sample exhibited more than 80 mA h g−1 under 0.5 mA cm−2.