High resolution x-ray absorption and emission spectroscopy of LixCoO2single crystals as a function delithiation.
The effect of delithiation in LixCoO2is studied by high resolution Co K-edge x-ray absorption and x-ray emission spectroscopy. Polarization dependence of the x-ray absorption spectra on single crystal samples is exploited to reveal information on the anisotropic electronic structure. We find that the electronic structure of LixCoO2is significantly affected by delithiation in which the Co ions oxidation state tending to change from 3+  to 4+. The Co intersite (intrasite) 4p-3d hybridization suffers a decrease (increase) by delithiation. The unoccupied 3d t2gorbitals with a1gsymmetry, containing substantial O 2p character, hybridize isotropically with Co 4p orbitals and likely to have itinerant character unlike anisotropically hybridized 3d egorbitals. Such a peculiar electronic structure could have significant effect on the mobility of Li in LixCoO2cathode and hence the battery characteristics.
CELLS-ALBA, Carretera BP 1413, de Cerdanyola del Valles a Sant Cugat del Valles, Km. 3,3 08290 Cerdanyola del Valles, Barcelona, Spain. European Synchrotron Radiation Facility, BP220, F-38043 Grenoble Cedex, France.
L
L
Simonelli
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E
Paris
C
C
Iwai
K
K
Miyoshi
J
J
Takeuchi
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T
Mizokawa
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NL
Saini