Effect of synthesis temperature on the properties of LiFePO4/C composites prepared by carbothermal reduction

LiFePO4/C composite cathode materials were synthesized by carbothermal reduction method using inexpensive FePO4 as raw materials and glucose as conductive additive and reducing agent. The precursor of LiFePO4/C was characterized by differential thermal analysis and thermogravimetry. The microstructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and particle size analysis. Cyclic voltammetry (CV) and charge/discharge cycling performance were used to characterize their electrochemical properties. The results showed that the LiFePO4/C composite synthesized at 650 degrees C for 9 h exhibited the most homogeneous particle size distribution. Residual carbon during processing was coated on LiFePO4, resulting in the enhancement of the material's electronic properties. Electrochemical measurements showed that the discharge capacity first increased and then decreased with the increase of synthesis temperature. The optimal sample synthesized at 650 degrees C for 9 h exhibited a highest initial discharge capacity of 151.2 mAh g(-1) at 0.2 C rate and 144.1 mAh g(-1) at 1 C rate with satisfactory capacity retention rate. (C) 2008 Elsevier B.V. All rights reserved.