Li-ion diffusion in highly (003) oriented LiCoO2 thin film cathode prepared by pulsed laser deposition

A pure, well crystallized and highly (003) 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 4.2V 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 2X10-13cm2/s. EIS revealed that the charge-transfer resistance obviously decreased above 3.90V and changed little up to 4.22V. The diffusion coefficients obtained from EIS were in the order of 10-12cm2/s while they were in the range of 6X10-13 and 8X10-12cm2/s from PITT, depending on the potentials.