Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 15 No. 4 August 2005|
with enhanced electrochemical performance
（School of Metallurgy Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: LiFePO4/C composite was synthesized by high temperature solid-state reaction using iron(Ⅱ) oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of carbohydrate dissolved in the dispersant(ethanol) as carbon sources added to the synthetic precursor. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy observations(SEM), charge/discharge test, cyclic voltammetry(CV) and carbon analysis. The results show that the synthesis of LiFePO4/C has ordered olivine structure. The carbon has two advantages: optimizing particle size of LiFePO4 and increasing the electronic conductivity and high Li+ diffusivity. The cathode material can demonstrate a charge/discharge flat voltage of 3.4V(vs Li+/Li). Especially the active material with 15% and 20% carbohydrate added according to the final product of lithium iron phosphate shows very good electrochemical performance delivering about initial 150.2mA•h•g-1 and 162.0mA•h•g-1 specific capacity respectively at 0.1C rate and the carbon contents in the final production are only 5.17% and 5.29%, respectively.
Key words: Li-ion battery; cathode materials; LiFePO4; carbon-coated