Electrochemical investigations on electrostatic spray deposited LiMn₂O₄ films

LiMn₂O₄ films have been prepared using an electrostatic spray deposition (ESD) technique at 400 °C. The deposited films are investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical quartz crystal microbalance (EQCM), cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS). Analysis of LiMn₂O₄ films using XRD and SEM indicates the formation of a LiMn₂O₄ single spinel phase with a uniform and dense film. On the other hand, electrochemical investigation in a non-aqueous electrolyte (1M LiClO₄+EC+DEC) suggests the formation of surface film after the initial dissolution of Li₂CO₃ layer, the mass of surface film has been calculated from the resonant frequency curve and is about 1.2% of entire LiMn₂O₄ film. The results of CV, EQCM and EIS studies are discussed in terms of changes in surface electrochemical properties during the lithium insertion-extraction process.