Construction of E-pH diagram and experimental study on wet synthesis of FePO₄ as the precursor of cathode materials

¹ School of Intelligent Manufacturing, Jianghan University, Wuhan, China
² The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, China

^* Corresponding author: xueping20011982@163.com

Abstract

The preparation of FePO⁴ as a precursor by co-precipitation method is widely used, Due to the lack of the guidance of thermodynamic theory, The prepared FePO₄ often contains impurity phase, which leads to unsatisfactory performance of LiFeO₄. The E-pH diagram of Fe-P-H₂O system at the temperature of 25℃ were drawn through the basic E-pH principle with a number of thermodynamic data. According to the E-pH Diagram, the pH value is approximately 2.5, and the FePO₄ with less impurity can be prepared by adding proper oxidant. Base on the above mentioned condition, a simple verification experiment was carried out. The results showed that the prepared iron FePO₄ had fewer impurities, which provided a theoretical basis for preparing high-performance LiFeO₄.