Li+-ion diffusion in LiCoO2 thin film prepared by the poly(vinylpyrrolidone) sol-gel method

LiCoO2 thin film was successfully prepared by the PVP sol-gel method. The films were applied for evaluating chemical diffusion coefficients of Li+ ion (D) in LiCoO2 matrix, which was estimated by three different electrochemical methods, such as cyclic voltammetry, (CV), the potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The apparent chemical diffusion coefficient of Li+ ion in LiCoO2 film was preliminarily calculated to be 4.2 X 10-13 cm2 s-1 from CV. EIS exhibited 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. D obtained from EIS ranged from 10-13 to 10-12 cm2 s-1 at various electrode potentials. From PITT, D were estimated to be ~10-12 cm2 s-1 at various electrode potentials