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

Electrochemical lithium intercalation in thin films of porous nanostructure d TiO2 and dense electron-beam evaporated TiO2 (anatase) is investigated wi th ill situ X-ray diffraction (XRD). A complete and reversible phase transf ormation from tetragonal anatase TiO2 to orthorhombic anatase Li0.5TiO2 is observed. The maximum amount of lithium that can be dissolved in anatase Ti O2 before the phase transformation occurs is estimated to be 0.05 Li/Ti. Fo r nanostructured samples, the XRD spectra before, and after insertion were fitted with some of the lattice parameters of the two phases as fit variabl es. For the Li0.5TiO2 phase values of 3.85, 4.06. and 8.95 Angstrom are fou nd for the a, b, and c, axes, respectively, in good agreement with data rep orted for chemically lithiated anatase TiO2 powder, implications of the pha se 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.