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Local coordination of Fe3+ in Li[Co0.98Fe0.02]O2 as cathode material for lithium ion batteries—multi-frequency EPR and Monte-Carlo Newman-superposition model analysis

Jakes, Peter and Erdem, Emre and Ozarowski, Andrew and Tol, Johan van and Buckan, Ronny and Mikhailova, Daria and Ehrenberg, Helmut and Eichel, Rüdiger-A. (2011):
Local coordination of Fe3+ in Li[Co0.98Fe0.02]O2 as cathode material for lithium ion batteries—multi-frequency EPR and Monte-Carlo Newman-superposition model analysis.
In: Physical Chemistry Chemical Physics, pp. 9344-9352, 13, (20), ISSN 1463-9076, [Online-Edition: http://dx.doi.org/10.1039/C0CP02048F],
[Article]

Abstract

The local coordination of the Fe3+-centers in Li[Co0.98Fe0.02]O2 cathode materials for lithium-ion batteries has been investigated by means of XRD and multi-frequency EPR spectroscopy. EPR clearly showed the Fe3+ being in a high-spin state with S = [fraction five-over-two]. The set of spin-Hamiltonian parameters obtained from multi-frequency EPR experiments with Larmor frequencies ranging between 9.8 and 406 GHz was transformed into structural information by means of an expansion to standard Newton-superposition modeling, termed as Monte-Carlo Newman superposition modeling. Based on this analysis, an isovalent incorporation of the Fe3+-ions on the Co3+-sites, i.e. FexCo, has been shown. With that respect, the positive sign of the axial second-order fine-structure interaction parameter B02 is indicative of an elongated oxygen octahedron, whereas B02 < 0 points to a compressed octahedron coordinated about the Fe3+-center. Furthermore, the results obtained here suggest that the oxygen octahedron about the Fe3+-ion is slightly distorted as compared to the CoO6 octahedron, which in turn may impose mechanical strain to the cathode material.

Item Type: Article
Erschienen: 2011
Creators: Jakes, Peter and Erdem, Emre and Ozarowski, Andrew and Tol, Johan van and Buckan, Ronny and Mikhailova, Daria and Ehrenberg, Helmut and Eichel, Rüdiger-A.
Title: Local coordination of Fe3+ in Li[Co0.98Fe0.02]O2 as cathode material for lithium ion batteries—multi-frequency EPR and Monte-Carlo Newman-superposition model analysis
Language: English
Abstract:

The local coordination of the Fe3+-centers in Li[Co0.98Fe0.02]O2 cathode materials for lithium-ion batteries has been investigated by means of XRD and multi-frequency EPR spectroscopy. EPR clearly showed the Fe3+ being in a high-spin state with S = [fraction five-over-two]. The set of spin-Hamiltonian parameters obtained from multi-frequency EPR experiments with Larmor frequencies ranging between 9.8 and 406 GHz was transformed into structural information by means of an expansion to standard Newton-superposition modeling, termed as Monte-Carlo Newman superposition modeling. Based on this analysis, an isovalent incorporation of the Fe3+-ions on the Co3+-sites, i.e. FexCo, has been shown. With that respect, the positive sign of the axial second-order fine-structure interaction parameter B02 is indicative of an elongated oxygen octahedron, whereas B02 < 0 points to a compressed octahedron coordinated about the Fe3+-center. Furthermore, the results obtained here suggest that the oxygen octahedron about the Fe3+-ion is slightly distorted as compared to the CoO6 octahedron, which in turn may impose mechanical strain to the cathode material.

Journal or Publication Title: Physical Chemistry Chemical Physics
Volume: 13
Number: 20
Divisions: DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > B - Characterisation > Subproject B1: EPR-Investigations of defects in ferroelectric ceramic material
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > B - Characterisation > Subproject B4: In situ investigations of the degradation of intercalation batteries and their modelling
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > B - Characterisation
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 15 Sep 2011 14:21
Official URL: http://dx.doi.org/10.1039/C0CP02048F
Additional Information:

SFB 595 Cooperation B1, B4

Identification Number: doi:10.1039/C0CP02048F
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