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

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.