High-rate properties of LiFePO4/carbon composites as cathode materials for lithium-ion batteries

Electrochemical properties of LiFePO4/carbon composites were investigated to achieve a high-rate lithium electrode performance. LiFePO4/ carbon composites were synthesized by a hydrothermal reaction of a solution of FeSO4 center dot 7H(2)O, H3PO4, and LiOH center dot H2O mixed with carbon powders under nitrogen atmosphere followed by annealing under 1% H-2-99% Ar atmosphere. Particle size of the obtained LiFePO4/carbon composites observed by scanning electron microscopy was less than 100 nm. At a high current density of 1000 mA g(-1), the LiFePO4/carbon composites showed a high discharge capacity of 113 mA h g(-1), and a flat discharge potential plateau was observed around 3.4 V. The discharge capacity at the high current density, 85% of that at a low current density of 30 mA g(-1), is a quite high value for LiFePO4 cathodes. Homogeneous microstructure consisting of small particles contributed to the high-rate properties of the LiFePO4/carbon composites. (C) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.