Preparation of Micro-Nano-Structured FePO4·2H2O for LiFePO4 Cathode Materials by the Turbulent Flow Cycle Method.

Abstract

The micro–nano-structured FePO4·2H2O was prepared from mixed solution of FeSO4 oxidized in diluted H3PO4 with H2O2 and NaOH solution in the turbulent flow cycle state at 90 °C. The resulting products were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Constant current charge/discharge tests were adopted to investigate the electrochemical performance and the rate capability (from 0.1C to 5C) of the carbon-coated LiFePO4 composite materials prepared from the micro–nano-structured FePO4. The carbon-coated LiFePO4 composite materials deliver a high specific discharge capacity of 153.7 mAh·g–1, exhibit excellent cycle performance with 98.6% of the capacity retained after 30 cycles. This study demonstrates that the turbulent flow cycle method may be an economical and effective method for industrial production of fine and uniform micro–nano-structured FePO4·2H2O particles for LiFePO4 cathode materials for Li-ion batteries.