Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-29T08:15:52.369Z Has data issue: false hasContentIssue false
  • English
  • Français

X-ray Absorption and NMR Studies of LiNiCoO2 Cathodes Prepared by a Participate Sol-Gel Process

Published online by Cambridge University Press:  10 February 2011

S. Rostov ,
Y. Wang ,
M. L. denBoer ,
S. Greenbaum ,
C. C. Change  and
Prashant N. Kumta
S. Rostov
Affiliation:
Physics Department, Hunter College, CUNY, NY
Y. Wang
Affiliation:
Physics Department, Hunter College, CUNY, NY
M. L. denBoer
Affiliation:
Physics Department, Hunter College, CUNY, NY
S. Greenbaum
Affiliation:
Physics Department, Hunter College, CUNY, NY
C. C. Change
Affiliation:
Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA
Prashant N. Kumta
Affiliation:
Dept. of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA
Get access

Abstract

We have synthesized lithiated nickel oxide-based cathode materials containing stoichiometric and excess lithium using a new low temperature colloidal paniculate sol-gel process. The process yields a xerogel precursor that transforms to the crystalline oxide at 800 °C in 2h. We studied the Li environment with nuclear magnetic resonance (NMR) and that of the transition metal ions with x-ray absorption spectroscopy. We measured samples of LiNi1−xCoxO2, with x = 0 and 0.25. The effect on each composition of the incorporation of 5 mol % Li was also examined. The precursor material appears to have no Ni3+, as indicated x-ray absorption measurements, and is highly disordered, showing little sign of interatomic correlations beyond the nearest neighbor in extended x-ray absorption fine structure (EXAFS) spectra. The 7Li NMR line widths and spin-lattice relaxation (T1) behavior are dominated by strong interactions with the paramagnetic Ni3+. The presence of 5 % excess Li causes almost no change in NMR line width or T1 in the mixed (Ni/Co) cathode, but does produce an almost 30% reduction in line width for the pure LiNiO2, implying that Co stabilizes the structure. The near-edge x-ray absorption measurements show the local Ni environment is relatively unaffected by Co substitution, a result confirmed by EXAFS analysis. The heat-treated samples are highly ordered, and both the near-edge and extended analysis imply Co substitutes primarily for Ni2+, not Ni3+. The Jahn-Teller distortion is apparent in both the stoichiometric and Li-excess materials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 496: Symposium Y – Materials For Electrochemical Energy Storage & Conversion II… , 1997 , 427
Copyright
Copyright © Materials Research Society 1998

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Broussely, M., Perton, F., Biensan, P., Bodet, J.M., Labat, J., Lecerf, A., Delmas, C., Rougier, A., and Peres, J.P., Journal of Power Sources 54, 109 (1995).10.1016/0378-7753(94)02049-9Google Scholar
2. Ohzuku, Tsutomu, Ueda, Atsushi, Nagayama, Masatoshi, Iwakoshi, Yasunobu and Komori, Hideki; Electrochimica Acta, 38, 1159 (1993).10.1016/0013-4686(93)80046-3Google Scholar
3. Banov, B., Bourilkov, J., and Mladenov, M., Journal of Power Sources 54, 268 (1995).10.1016/0378-7753(94)02082-EGoogle Scholar
4. Caurant, D., Baffier, N., Garcia, B., and Pereira-Ramos, J.P., Solid State Ionics 91, 45 (1996).Google Scholar
5. Chang, Chun-Chieh, Scarr, N. and Kumta, P.N., Proceedings of the Joint International Meeting of the ECS and ISE, Paris, France, 31 August - 5 September 1997.Google Scholar
6. Rehr, J. J., Albers, R. C., and Zabinsky, S. I., Phys. Rev. Lett. 69, 3397 (1992),Google Scholar
and Ab initio Multiple-Scattering X-ray Absorption Fine Structure and X-ray Absorption Near Edge Structure Code, Copyright 1992, 1993, FEFF Project, Department of Physics, FM-15 University of Washington, Seattle, WA 98195.Google Scholar
7. Dyer, L. D., Borie, B. S. Jr., and Smith, G. P., J. Am. Chem. Soc. 76, 1499 (1954).Google Scholar
8. Mansour, A. N. and Melendres, C. A., J. Phys. Chem., 102, issue 002, 1998.Google Scholar
9. Chetai, A. R., Mahto, P. and Sarode, P.R., J. Phys. Chem. Solids 49, 279 (1988)Google Scholar
10. Pickering, I., George, G., Lewandowski, J., and Jacobson, A., J. Am. Chem. Soc., 115, 4144 (1993).Google Scholar
11. Rougier, A., Delmas, C., and Chadwick, A., Sol. State Comm. 94, 123 (1995).Google Scholar