Synthesis of Nano-Sized FePO4 Cathode Material via a Microemulsion Technique

A novelsynthetic method is developed to prepare nano-sized FePO4 powdersused as cathode materials of lithium ion batteries. The samples are preparedvia a microemulsion system in a H2O/cyclohexane/Triton x-100/n-butylalcohol, and then sinter at different temperatures (380°C，460°C，550°C，650°C)for 3h. The thermal stability，structure，morphology and particle size are investigated by means of TG/DSC, X-raydiffraction (XRD), field emission-scanning electron microscopy (FE-SEM), andthe electrochemical properties are characterized by cyclic voltammetry (CV) andgalvanostatic charge and discharge tests. Results show the grain size of FePO4particles sintered at 460°C and 380°C for 3h ranges from 10nm to 20nm, and thecrystal structure is amorphous. The initial discharge specific capacity of FePO4cathode sintered at 460°C for 3h reaches 139mAhg-1 and 110mAh/g,respectively, at 0.1C and 0.3C. Increasing sintering temperature leads to thesmall particles agglomeration and the crystalline growth, and the crystalstructure changes from amorphous to trigonal when the sintering temperature isup to 550°C. The discharge specific capacity also decreases with the increase ofthe sintering temperature. These results suggest that nano-sized particles andamorphous structure can significantly improve the performances of FePO4cathode.