A PEG assisted sol-gel synthesis of LiFePO4 as cathodic material for lithium ion cells

In order to obtain fine-particle LiFePO4 with excellent electrochemical performance, LiFePO4/C powders were synthesized by a poly(ethylene glycol) (PEG) assisted sol-gel method. All samples were characterized by X-ray powder diffraction and scanning electron microscopy, and their electrochemical properties were investigated by cycle voltammograms and charge-discharge tests. The sample, synthesized with the n(PEG)/n(LFP) = 1: 1 under sintering temperature of 600 degrees C, possesses the global morphology and particle size of about 100 nm. This sample delivers the first discharge capacity of 162 mAh g(-1), i.e. 95.3% of the theoretical capacity, at the 15 mA g(-1) discharge current between 2.5 and 4.0 V (versus Li/Li+). The sample also displays a robust rate capability and stable cycle-life. The improved electrochemical performance originates mainly from the fine particle of nanometric dimension, regular global morphology and uniform dispersing in the product as well as the increased electronic conductivity by carbon coating. (c) 2006 Elsevier Ltd. All rights reserved.