The Effects of Au Loading on the Electrochemical Properties of Fe1.5(PO4)(OH) Cathode Material for Lithium-Ion Batteries

Fe1.5(PO4)(OH) loaded with Au (mass ratio = 0, 0.5, 2, 4, 6 %) was synthesized via two steps, combining microemulsion and hydrothermal techniques, and the effects of the Au loading on the electrochemical properties of Fe1.5(PO4)(OH) cathode material were investigated. The structure and morphology were studied by means of X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM), and the electrochemical performances were characterized by galvanostatic charge and discharge tests. The XRD patterns showed that the Au loading modification did not affect the structure of Fe1.5(PO4)(OH). From the charge and discharge test, it was found that when the mass ratio of Au loading was 2 % the sample exhibited excellent electrochemical properties with an initial specific capacity of 182 mAhg−1 at 0.1 C and less fading of the specific capacity, retaining about 165 mAhg−1 after 25 cycles, which demonstrated that the Au loading is an effective way to improve the electron conductivity of Fe1.5(PO4)(OH). What is more, the electrochemical properties of Fe1.5(PO4)(OH)/Au synthesized at 150 °C for 24 h with a discharge specific capacity of 182 mAhg−1 are better than those of the sample synthesized at 180 °C for 24 h with a discharge specific capacity of 121 mAhg−1, which is attributed to the crystal growth of particles at high hydrothermal temperatures, showing that the particle size also has a significant influence on the electrochemical performance of electrode materials.