Electrochemical properties of the carbon-coated LiFePO4 as a cathode material for lithium-ion secondary batteries

In this study the effect of the carbon coating on the electrochemical properties of LiFePO4 as a cathode for Li-ion batteries were investigated. The carbon-coated LiFePO4 particles were synthesized by the mechanochemical process and one-step heat treatment. Microscopic observations using SEM and TEM revealed that the carbon coating reduced the particle size of the LiFePO4. The carbon-coated LiFePO4 showed much better performances in terms of the discharge capacity and cycle stability than bare LiFePO4. It was confirmed that the carbon coating decreased the migration distance of Li-ion and enhanced the charge transfer from CV and ac impedance measurements. The improved electrochemical properties of the carbon-coated LiFePO4 were, therefore, attributed to the reduced particle size and enhanced electrical contacts by carbon. (c) 2006 Elsevier B.V. All rights reserved.