Li-ion diffusion in highly (0 0 3) oriented LiCoO2 thin film cathode prepared by pulsed laser deposition

A pure, well crystallized and highly (0 0 3) oriented LiCoO2 thin film was deposited on stainless steel substrates by pulsed laser deposition. The overall diffusion coefficients of lithium-ion in the potential range between 3.85 and 4.2 V were measured by three different electrochemical methods namely, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiostatic intermittent titration technique (PITT). From CV, the apparent chemical diffusion coefficient of lithium-ion was estimated to be 2 × 10−13 cm2/s. EIS revealed that the charge-transfer resistance obviously decreased above 3.90 V and changed little up to 4.22 V. The diffusion coefficients obtained from EIS were in the order of 10−12 cm2/s while they were in the range of 6 × 10−13 and 8 × 10−12 cm2/s from PITT, depending on the potentials.