Li diffusion in spinel LiNi0.5Mn1.5O4thin films prepared by pulsed laser deposition

Spinel LiNi 0.5 Mn 1.5 O 4 thin film electrodes of 0.5 μm thickness were prepared on polished stainless steel (SS) substrates by pulsed laser deposition. Kinetics and mass-transport of Li intercalation/deintercalation were investigated by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiostatic intermittent titration technique (PITT). The CV measurements indicate that there exists a small amount of Mn 3 + in the film and Li transportation is controlled by diffusion at high scan rates. EIS measurements show a potential independent low charge-transfer resistance region between 4.1 and 4.7 V and a stable surface layer resistance through the full potential range. The chemical diffusion coefficients of Li in the LiNi 0.5 Mn 1.5 O 4 thin film obtained by EIS and PITT have been found to be in the range of 10 −12 –10 −10 cm 2 s −1 depending on the electrode potential. Two minima were found for from PITT at potentials close to the peak potentials of the corresponding CV.