Nonstoichiometric Lithium Iron Phosphate Synthesized by Hydrothermal Route

Article Preview

Abstract:

Lithium iron phosphate with varied Fe/P molar ratio was synthesized from LiOH, FeSO4, and H3PO4 by hydrothermal route at 180°C for 6 h. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), chemical analysis, and constant current charge-discharge cycling test. It was found that at the same pH value of reaction, the Fe/P ratio had a major effect on the content of impurity phase, crystal structure and electrochemical performance of the samples. However, it had a minor effect on the morphology of the samples. A single phase structure was obtained for the samples with the Fe/P ratio of 0.97-1.02. The sample with the Fe/P ratio of 0.97 exhibited the best electrochemical behaviors, whose specific discharge capacities could reach 152.7, 144.8 and 133.2mAhg-1 at 0.2C, 1C and 5C rate, respectively, with the capacity retention rate close to 100% after 50 cycles at 5C. It is believed that the excellent electrochemical performance of specific discharge capacity, rate capability and cycling stability is attributed to the nonstoichiometry of LiFePO4, which results in the Li-rich defective crystal structure and the decrease of cell parameters, thus facilitating the discharge behaviors at high rates.

You might also be interested in these eBooks

Info:

Periodical:

Pages:

118-123

Citation:

Online since:

December 2010

Export:

Price:

Permissions CCC:

Permissions PLS:

Сopyright:

© 2011 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

[1] S.Y. Chung, J.T. Bloking, Y.M. Chiang: Nat. Mater. Vol. 1 (2002) , p.123.

Google Scholar

[2] J. R. Ying, M. Lei, C. Y. Jiang, et al.: J. Power Sources Vol. 158 (2006), p.543.

Google Scholar

[3] J. F. Ni, H. H. Zhou, J. T. Chen, et al.: Chinese J. Inorg. Chem. Vol. 21 (2005), p.472.

Google Scholar

[4] D. Wang, H. Li, S. Shi, et al.: Electrochim. Acta. Vol. 50 (2005) , p.2955.

Google Scholar

[5] G. X. Wang, S. L. Bewlay, K. Konstantinov, et al.: Electrochim. Acta. Vol. 50 (2004), p.443.

Google Scholar

[6] J. F. Ni, H. H. Zhou, J. T. Chen, et al.: Mater Lett. Vol. 59 (2005), p.2361.

Google Scholar

[7] M. Zhang, L. F. Jiao, H. T. Yuan, et al.: Solid State Ionics. Vol. 177 (2006), p.3309.

Google Scholar

[8] H. Xie, Z. T. Zhou: Electrochim. Acta. Vol. 51 (2006) , p. (2063).

Google Scholar

[9] J. F. Ni, H. H. Zhou, J. T. Chen, et al.: Acta Phys. -Chim. Sin. Vol 20 (2004), p.582.

Google Scholar

[10] P. S. Herle, B. Ellis, N. Coombs, et al.: Nat. Mater. Vol. 3 (2004), p.147.

Google Scholar

[11] C. Delacourt, C. Wurm, L. Laffont, et al.: Solid State Ionics. Vol. 177 (2006), p.333.

Google Scholar

[12] S. Franger, C. Benoit, C. Bourbon, et al.: J. Phys. Chem. Solids. Vol. 67 (2006), p.1338.

Google Scholar

[13] M. R. Yang, W. H. Ke, S. H. Wu: J. Power Sources. Vol. 165 (2007), p.646.

Google Scholar

[14] X. Ou, G. Liang, L. Wang, et al.: J. Power Sources. Vol. 184 (2008), p.543.

Google Scholar

[15] K. Dokko, S. Koizumi, K. Sharaishi, et al.: J. Power Sources. Vol. 165 (2007), p.656.

Google Scholar

[16] J. Chen, S. Wang, M. S. Whittingham: J. Power Sources. Vol. 174 (2007), p.442.

Google Scholar