Preparation and characterization of nanoscale LiFePO4 cathode materials by a two-step solid-state reaction method

In order to obtain high-performance nanoscale LiFePO4 cathode materials for lithium-ion batteries, CH3COOLi center dot 2H(2)O, FeC2O4 center dot 2H(2)O, and NH4H2PO4 were used as raw materials to prepare the precursors of LiFePO4 by room-temperature solid-state reaction method firstly; then, LiFePO4 cathode materials were synthesized by high heating solid-state reaction method. The influence of temperature on the crystal structure, microstructure, and electrochemical properties were studied by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and charge-discharge performance test. It was indicated that the olivine-phase LiFePO4 not only presented nano-sized particles in the range of 40-80 nm, but also showed excellent initial discharge specific capacity of about 155 mAh/g at 0.2 C at a sintering temperature of 700 A degrees C and possessed good cycle performance. This preparation method without any solvent and carbon source addition could realize industrialized production of single-phase nano-LiFePO4.