Improvement of Electrochemical Performance of LiFePO4 by Carbon Coating and Morphology Control into Porous Structure

In this study, the method to improve the electrochemical performance of LiFePO4 by carbon coating and morphology control into porous structure was studied. The synthesis of LiFePO4 was done by coprecipitation method by two step procedure. In the first step FePO4 precursor was synthesized by coprecipitation method, followed by impregnation of lithium into the precursor at 750 degrees C. The carbon coating was done by both physical and chemical coating processes. Using the physical coating process, the amount of coating layer was 6% and the capacity achieved was 125 mAh/g. In case of chemical coating process, the active material delivered 130 similar to 140 mAh/g, which is about 40% improvement of delivered capacity compared to uncoated LiFePO4. For the morphology control into porous structure, we added nano particles of Al2O3 or SiO2 into the active materials and formed the nanocomposite of (Al2O3 or SiO2)/LiFePO4. Between them, SiO2/LiFePO4 porous nanocomposite showed larger capacity of 132 mAh/g