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Journal of Nanotechnology
Volume 2009, Article ID 176517, 10 pages
http://dx.doi.org/10.1155/2009/176517
Review Article

Structural and Electrochemical Characterization of Pure and Nanocomposite C- Cathodes for Lithium Ion Rechargeable Batteries

1Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00931-3343, USA
2Centre of Material Sciences, University of Allahabad, Allahabad 211002, India
3Materials Science Center, Indian Institute of Technology, Kharagpur 721302, India
4Department of Physics, University of Puerto Rico, Mayaguez, PR 00680-9016, USA

Received 14 March 2009; Revised 12 August 2009; Accepted 2 December 2009

Academic Editor: Ram B. Gupta

Copyright © 2009 Arun Kumar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Pure lithium iron phosphate () and carbon-coated (C-) cathode materials were synthesized for Li-ion batteries. Structural and electrochemical properties of these materials were compared. X-ray diffraction revealed orthorhombic olivine structure. Micro-Raman scattering analysis indicates amorphous carbon, and TEM micrographs show carbon coating on particles. Ex situ Raman spectrum of C- at various stages of charging and discharging showed reversibility upon electrochemical cycling. The cyclic voltammograms of and C- showed only a pair of peaks corresponding to the anodic and cathodic reactions. The first discharge capacities were 63, 43, and 13 mAh/g for C/5, C/3, and C/2, respectively for where as in case of C- that were 163, 144, 118, and 70 mAh/g for C/5, C/3, C/2, and 1C, respectively. The capacity retention of pure was 69% after 25 cycles where as that of C- was around 97% after 50 cycles. These results indicate that the capacity and the rate capability improved significantly upon carbon coating.