Hydrothermal synthesis of LiFePO4 powders as cathode material for li-ion batteries

Abstract

Phospho-olivine LiFePO4 have been intensively studied as lithium insertion cathode materials for next generation of Li-ion secondary batteries. LiFePO4 has an interesting theoretical specific capacity of about 170 mAhg-1, a good cycle stability and technically attractive flat voltage versus current profile of 3.45 V versus Li+/Li. A further advantage of this material, thanks to its stability, is the improved safety at high temperatures. In this work, LiFePO4 was prepared by hydrothermal reaction starting from water solutions of LiOH, FeSO4 and H3PO4. After hydrothermal reaction the obtained powder was heat treated in reduction atmosphere to avoid oxidation of Fe2+ to Fe3+. Powder was additionally treated by high energy ball-milling. The structural and morphological properties of LiFePO4 powder was characterized by X- ray diffraction and scanning electron microscopy. LiFePO4/Li battery was characterized electrochemically by constant current charge-discharge cycling.