On the behavior of the LixNiO2 system: an electrochemical and structural overview

Delmas, C. and Peres, J.P. and Rougier, A. and Demourgues, A. and Weill, F. and Chadwick, Alan V. and Broussely, M. and Perton, F. and Biensan, P and Willmann, P. (1997) On the behavior of the LixNiO2 system: an electrochemical and structural overview. In: 8th International Meeting on Lithium Batteries (IMLB 8), jUNE 16-21, 1996, Nagoya, Japan. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Lithium nickel oxide exhibits a departure from stoichiometry (Li1-zNi1+zO2) consisting in the presence of extra-nickel ions within the lithium sites. Using optimized experimental synthesis conditions, compositions very close to the ideal stoichiometry (z = 0.02) can be obtained. By using the sensitivity of the lithium site isotropic temperature factor to the stoichiometry, the amount of extra-nickel ions can be determined in a very precise way. The loss of reversibility at the first cycle is mainly related to the change in the oxidation state of the extra-nickel ions, which induces a local collapse of the structure and makes difficult the lithium re-intercalation, A systematic structural study of LixNiO2 phases has been performed by extended X-ray absorption fine structure (EXAFS) as well as X-ray and electron diffraction. In the case of the starting Li0.98Ni1.02O2 phase, a local distortion of the NiO6 octahedra, resulting from a dynamic Jahn-Teller effect of low spin trivalent nickel ions has been evidenced from the EXAFS study. For the partially de-intercalated materials (0.50 < x < 0.75) which crystallize in the monoclinic system, the EXAFS study shows that the NiO6 octahedra are only slightly distorted due to the occurrence of a hopping phenomenon between Ni-IV and Ni-III. Electron diffraction experiments show the existence of a superstructure due to a peculiar lithium-ion ordering. Systematic electrochemical studies have shown that this ordering is strongly sensititve to the presence of extra-nickel ions. (C) 1997 Elsevier Science S.A.

Item Type: Conference or workshop item (Paper)
Uncontrolled keywords: lithium; nickel oxides; intercalation
Depositing User: T. Nasir
Date Deposited: 24 Oct 2009 14:56
Last Modified: 29 Apr 2014 08:24
Resource URI: https://kar.kent.ac.uk/id/eprint/18391 (The current URI for this page, for reference purposes)
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