Solid Chemical Reaction by Microwave Heating for the Synthesis of LiFePO₄ Cathode Material

Abstract

LiFePO₄ has been synthesized using FeC₂O₄•2H₂O, LiOH•H₂O and NH₄H₂PO₄ as raw materials by a temperature controllable microwave heating oven. The products were characterized by X-ray diffraction, scanning electron microscope and electrochemical methods. Measurement of dielectric properties of individual raw materials and products at a constant microwave frequency revealed that the starting mixture preheated at 320°C as well as added acetylene black were well microwave absorbers. Single phase olivin-type LiFePO₄ with uniform and fine particle sizes was successfully synthesized by microwave heating at 350°C in 15 min. The LiFePO₄ cathode materials thus obtained had a higher discharge capacity and better cycle performance than those of the LiFePO₄ sample by a conventional solid-state reaction.