Premium
Raman investigation of the structural changes in anatase Li x TiO 2 upon electrochemical lithium insertion
Author(s) -
BaddourHadjean Rita,
Bach Stéphane,
Smirnov Mikhail,
PereiraRamos JeanPierre
Publication year - 2004
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1200
Subject(s) - raman spectroscopy , orthorhombic crystal system , anatase , tetragonal crystal system , propylene carbonate , lithium (medication) , analytical chemistry (journal) , electrochemistry , chemistry , raman scattering , materials science , crystal structure , crystallography , optics , medicine , biochemistry , physics , electrode , photocatalysis , chromatography , endocrinology , catalysis
Micro‐Raman spectrometry and x‐ray diffraction (XRD) experiments were performed on the anatase Li x TiO 2 system (0 ≤ x ≤ 0.6) produced from the electrochemical discharge of a TiO 2 composite cathode in propylene carbonate LiClO 4 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) Li 0.5 TiO 2 orthorhombic phase is clearly evidenced. A theoretical analysis of the lattice dynamics suggested a complete interpretation of the experimental Raman spectra in the Li x TiO 2 system, which provided valuable information on the Li atom positions and coordination in LT. Taking into account the possibility of rather short LiO distances, the complex band structure in the high‐wavenumber region is assigned to the LiO vibrations. Furthermore, spectra simulation offers an explanation for the new shape of the TiO 2 lattice modes observed in the low‐wavenumber region. Copyright © 2004 John Wiley & Sons, Ltd.