Research Update: Retardation and acceleration of phase separation evaluated from observation of imbalance between structure and valence in LiFePO{sub 4}/FePO{sub 4} electrode

LiFePO{sub 4} is a potential positive electrode material for lithium ion batteries. We have experimentally observed an imbalance between the valence change of Fe ions and the structure change from the LiFePO{sub 4} phase to the FePO{sub 4} phase during delithiation by simultaneous in situ XRD and XA...

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Bibliographic Details
Published in:APL materials 2014-07, Vol.2 (7)
Main Authors: Tokuda, Kazuya, Kawaguchi, Tomoya, Ichitsubo, Tetsu, Matsubara, Eiichiro, Fukuda, Katsutoshi
Format: Article
Language:English
Subjects:
ABSORPTION SPECTROSCOPY
ELECTRIC BATTERIES
ELECTRODES
IRON IONS
IRON PHOSPHATES
LITHIUM IONS
MATERIALS SCIENCE
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
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Summary:LiFePO{sub 4} is a potential positive electrode material for lithium ion batteries. We have experimentally observed an imbalance between the valence change of Fe ions and the structure change from the LiFePO{sub 4} phase to the FePO{sub 4} phase during delithiation by simultaneous in situ XRD and XANES measurements in an LiFePO{sub 4}/FePO{sub 4} electrode. The ratio of structure change to valence change clearly indicates that the phase separation from LiFePO{sub 4} to FePO{sub 4} is suppressed at the beginning of delithiation, while it is accelerated at the latter stage, which is due to the coherent strain caused by the lattice misfit between the two phases.
ISSN:2166-532X
2166-532X
DOI:10.1063/1.4886555