Thin films were successfully prepared by the PVP sol-gel method. The films were applied for evaluating the chemical diffusion coefficient of Li+ ions in LiCoO2 matrix, which was estimated by three different electrochemical methods, such as cyclic voltammetry, the potentiostatic intermittent titration technique, and electrochemical impedance spectroscopy. The apparent chemical diffusion coefficient of Li+ ion in LiCoO2 film was calculated to be 4.2 x 10–13cm2/s by cyclic voltammetry. Electrochemical impedance spectroscopy showed that the charge-transfer resistance was dramatically decreased at 3.90 V vs. Li/Li+ during a charge state, indicating that Li+ ion was easily extracted from LiCoO2 matrix at this potential. The chemical diffusion coefficients obtained from EIS ranged from 10–13 to 10–12cm2/s at various electrode potentials. From the potentiostatic intermittent titration technique, the chemical diffusion coefficients were estimated to be ~10–12cm2/s at various electrode potentials.

Li+-Ion Diffusion in LiCoO2 Thin Film Prepared by the Poly(vinylpyrrolidone) Sol-Gel Method. Y.H.Rho, K.Kanamura: Journal of the Electrochemical Society, 2004, 151[9], A1406-11