Synthesis and Modification of Iron-based Cathode Materials: Iron Phosphate for Lithium Secondary Batteries

Iron-based cathode material, iron phosphate, was prepared by homogeneous co-precipitation followed by spray drying method, where Ce3+doping modifications were carried out to improve the electrical conductivity. Considering that the relationship between structures and performances, calcining temperature and doping concentration were investigated. The physicochemical property of the precursor was analyzed using TG–DSC, the structures and morphologies of samples were characterized by X-ray diffraction and scanning electron microscopy, electrochemical behaviors of samples were analyzed using charge–discharge tests and electrochemical impedance spectrum tests. Results show that the electrochemical performance of iron phosphate was improved by the synthesis condition optimization and doping modification. Fe0.98Ce0.02PO4 calcined at 460°C showed the highest discharge capacity of 100.3 mAh/g for the initial cycle at 0.05C. In addition, the doping mechanism for FePO4 was discussed in this paper.