HYDROTHERMAL SYNTHESIS OF LiFePO₄ FOR RECHARGEABLE LITHIUM BATTERIES

Abstract

LiFePO₄ as a cathode material for rechargeable lithium batteries was prepared by hydrothermal process at 170°C under inert atmosphere. The starting materials were LiOH·H₂O, FeSO₄·xH₂O and (NH₄)₃PO₄·3H₂O. The electrochemical properties of LiFePO₄ were characterized in a mixed solvent of ethylene carbonate and diethyl carbonate (1:1 in volume) containing 1.0 mol dm^-3LiClO₄. The LiFePO₄ synthesized by hydrothermal process exhibited a discharge capacity of 90 mA h g^-1, which was considerably smaller than theoretical capacity (170 mA h g^-1). The annealing of LiFePO₄ at 400°C in argon atmosphere was effective in increasing the discharge capacity. The discharge capacity of the annealed LiFePO₄ was 150 mA h g^-1.