Lifepo < Sub > 4 < / Sub > / C Preparation And Electrochemical Properties Of The Nanocomposites

In this thesis,5μm LiFePO₄microspheres were synthesized by hydrothermalmethod using ferrous gluconate and lithium dihydrogen phosphate as raw materials,and SDBS as surfactant, respectively. The optimized synthesis parameters ha ve beendetermined by considering the effects of reaction temperatures, the amount of SDBSand the reaction concentrations. After carbonized at500℃, the material shows thebest electrochemical performance. The discharge capacity can reach115mAh/g and108mAh/g at0.2C and0.5C, respectively.LiFePO₄nanoplates with the thickness of50nm were obtained by hydrothermalmethod using LiOH, FeSO₄and H3PO₄as raw materials, HMT as additive,respectively. By evaluating the reaction temperature and time, the amount of HMT,pH value of the solution, the optimized synthesis condition has been chosen. Aftermixed with carbon using rheological method, the sample with carbon content3%andcalcined at700℃gives the best electrochemical performance. The0.2C dischargecapacity can reach130mAh/g. The capacity remains95%after20cycles at roomtemperature.50nm FePO₄nanoparticles were synthesized through a low-temperature solutionmethod and lithiated to obtain LiFePO₄/C nanoparticles by rheological method. SEMand TEM results show that the particle size is about50nm. Electrochemicalmeasurement results in a rather good performance. The0.3C discharge capacity canreach160mAh/g, and the capacity remains98%after20cycles at room temperature.