Entropy of Li intercalation in LixCoO2

Yvan Reynier, Jason Graetz, Tabitha Swan-Wood, Peter Rez, Rachid Yazami, Brent Fultz

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Abstract

The entropy of lithiation of LixCoO2 for 0.5 < x ≤ 1.0 was determined from measurements of the temperature dependence of equilibrated voltages of electrochemical cells. Measured changes in the entropy of the lithiation reaction were as large as 9.0 kB/atom, and as large as 4.2 kB/atom within the "O3" layered hexagonal structure of LixCoO2. Three contributions to the entropy of lithiation for the O3 phase were assessed by experiment and calculation. The phonon entropy of lithiation was determined from measurements of inelastic neutron scattering. Phonon entropy can account for much of the negative entropy of lithiation, but its changes with lithium concentration were found to be small. Electronic structure calculations in the local density approximation gave a small electronic entropy of lithiation of the O3 phase. The configurational entropy from lithium-vacancy disorder was large enough to account for most of the compositional trend in the entropy of lithiation of the O3 phase if ordered structures exist at lithium concentrations of x = 1/2 and x = 5/6. The electrochemical measurements showed the existence of a two-phase region in the composition range between x = 5/6 and 0.95. Electronic structure calculations gave evidence that these phases were metallic and insulating, respectively. Changes of the electronic and configurational entropy were found to be of comparable importance for this metal-insulator transition.

Original languageEnglish (US)
Article number174304
Pages (from-to)1-7
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number17
DOIs
StatePublished - Nov 2004

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Intercalation
intercalation
Entropy
entropy
Lithium
lithium
Electronic structure
electronic structure
Local density approximation
Atoms
Inelastic neutron scattering
Metal insulator transition
Electrochemical cells
electrochemical cells
electronics
Vacancies
atoms
inelastic scattering
neutron scattering
insulators

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Entropy of Li intercalation in LixCoO2 . / Reynier, Yvan; Graetz, Jason; Swan-Wood, Tabitha; Rez, Peter; Yazami, Rachid; Fultz, Brent.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 70, No. 17, 174304, 11.2004, p. 1-7.

Research output: Contribution to journalArticle

Reynier, Y, Graetz, J, Swan-Wood, T, Rez, P, Yazami, R & Fultz, B 2004, 'Entropy of Li intercalation in LixCoO2 ', Physical Review B - Condensed Matter and Materials Physics, vol. 70, no. 17, 174304, pp. 1-7. https://doi.org/10.1103/PhysRevB.70.174304
Reynier, Yvan ; Graetz, Jason ; Swan-Wood, Tabitha ; Rez, Peter ; Yazami, Rachid ; Fultz, Brent. / Entropy of Li intercalation in LixCoO2 In: Physical Review B - Condensed Matter and Materials Physics. 2004 ; Vol. 70, No. 17. pp. 1-7.
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