TY - JOUR

T1 - Raman investigation of the structural changes in anatase Li xTiO2 upon electrochemical lithium insertion

AU - Baddour-Hadjean, Rita

AU - Bach, Stéphane

AU - Smirnov, Mikhail

AU - Pereira-Ramos, Jean Pierre

N1 - Copyright: Copyright 2008 Elsevier B.V., All rights reserved.

PY - 2004/7

Y1 - 2004/7

N2 - Micro-Raman spectrometry and x-ray diffraction (XRD) experiments were performed on the anatase LixTiO2 system (0 ≥ x ≥ 0.6) produced from the electrochemical discharge of a TiO2 composite cathode in propylene carbonate -LiClO4 solution at room temperature. Raman spectrum modifications indicate local structural and chemical changes as lithium enters the anatase host lattice. The existence of a tetragonal to orthorhombic phase transition is clearly demonstrated by the Raman and XRD measurements. Moreover, lithium extraction is only partially quantitative for Li uptake ≤0.5, as shown both from structural and electrochemical data in the 3-1.5 V potential range. For the first time, the Raman fingerprint of the lithium titanate (LT) Li0.5TiO2 orthorhombic phase is clearly evidenced. A theoretical analysis of the lattice dynamics suggested a complete interpretation of the experimental Raman spectra in the Li xTiO2 system, which provided valuable information on the Li atom positions and coordination in LT. Taking into account the possibility of rather short Li-O distances, the complex band structure in the high-wavenumber region is assigned to the Li-O vibrations. Furthermore, spectra simulation offers an explanation for the new shape of the TiO2 lattice modes observed in the low-wavenumber region.

AB - Micro-Raman spectrometry and x-ray diffraction (XRD) experiments were performed on the anatase LixTiO2 system (0 ≥ x ≥ 0.6) produced from the electrochemical discharge of a TiO2 composite cathode in propylene carbonate -LiClO4 solution at room temperature. Raman spectrum modifications indicate local structural and chemical changes as lithium enters the anatase host lattice. The existence of a tetragonal to orthorhombic phase transition is clearly demonstrated by the Raman and XRD measurements. Moreover, lithium extraction is only partially quantitative for Li uptake ≤0.5, as shown both from structural and electrochemical data in the 3-1.5 V potential range. For the first time, the Raman fingerprint of the lithium titanate (LT) Li0.5TiO2 orthorhombic phase is clearly evidenced. A theoretical analysis of the lattice dynamics suggested a complete interpretation of the experimental Raman spectra in the Li xTiO2 system, which provided valuable information on the Li atom positions and coordination in LT. Taking into account the possibility of rather short Li-O distances, the complex band structure in the high-wavenumber region is assigned to the Li-O vibrations. Furthermore, spectra simulation offers an explanation for the new shape of the TiO2 lattice modes observed in the low-wavenumber region.

KW - Anatase TiO

KW - Electrochemical lithium insertion

KW - Lattice dynamics

KW - Li vibrations

UR - http://www.scopus.com/inward/record.url?scp=3142672822&partnerID=8YFLogxK

U2 - 10.1002/jrs.1200

DO - 10.1002/jrs.1200

M3 - Article

AN - SCOPUS:3142672822

VL - 35

SP - 577

EP - 585

JO - Journal of Raman Spectroscopy

JF - Journal of Raman Spectroscopy

SN - 0377-0486

IS - 7

ER -