Lithium Intercalation into Titanium Dioxide Films from a Propylene Carbonate Solution

Intercalation of lithium from an LiClO4 propylene carbonate solution into thin-film TiO2 (rutile) electrodes produced by thermal oxidation of a titanium substrate are studied using cyclic voltammetry and impedance measurements at 0.01 to 105 Hz. An equivalent circuit adequately modeling the impedance spectra of TiO2- and LixTiO2 electrodes throughout the frequency range studied is proposed. The electrochemical characteristics of film electrodes, the reversibility of intercalation-deintercalation process, the effect of surface passivation on the lithium transfer rate, and the dependence of electric, kinetic, and diffusion parameters on the electrode potential (composition) are discussed. The diffusion coefficient of lithium in LixTiO2 is 10–12 cm2/s, as estimated by the impedance method.