In situ X-ray diffraction of lithium intercalation in nanostructured and thin film anatase TiO2

Electrochemical lithium intercalation in thin films of porous nanostructured TiO2 and dense electron-beam evaporated TiO2 (anatase) is investigated with ill situ X-ray diffraction (XRD). A complete and reversible phase transformation from tetragonal anatase TiO2 to orthorhombic anatase Li0.5TiO2 is observed. The maximum amount of lithium that can be dissolved in anatase TiO2 before the phase transformation occurs is estimated to be 0.05 Li/Ti. For nanostructured samples, the XRD spectra before, and after insertion were fitted with some of the lattice parameters of the two phases as fit variables. For the Li0.5TiO2 phase values of 3.85, 4.06. and 8.95 Angstrom are found for the a, b, and c, axes, respectively, in good agreement with data reported for chemically lithiated anatase TiO2 powder, implications of the phase transition fur the analysis of optical and electrochemical measurements on TiO2 films are briefly discussed. (C) 1999 The Electrochemical Society. S0013-4651(98)12-078-5. All rights reserved.