Li-ion transport kinetics in LiMn 2O 4 thin films prepared by radio frequency magnetron sputtering

Abstract

LiMn 2O 4 thin films were deposited on silica glass substrates by radio frequency (RF) magnetron sputtering. The films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Li-ion chemical diffusion coefficients D ˜ Li were measured by cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS) and limiting current density (LCD). The D ˜ Li values depended on the content of Li in Li x Mn 2O 4. It was found that the D ˜ Li values by CV, PITT and LCD were in the order of 10 −10, 10 −11 and 10 −12 cm 2 s −1, respectively, and those by EIS were in the range of 10 −9 to 10 −11 cm 2 s −1. The D ˜ Li values obtained by above methods were compared with those by an electron blocking method. It turned out that the D ˜ Li values by the electron blocking method were more comparable with those by EIS.