Evaluation of Band Edge Parameters, Li Ion Dynamics and Excellent Electrochemical Properties of Li4Ti5O12 Anode Thin Films

Abstract We report on band edge parameters calculated from the electrochemical data, work function, Li ion dynamics and excellent electrochemical properties of Li4Ti5O12 thin films prepared by RF sputtering technique. Raman spectra recorded at room temperature confirms the formation of Li4Ti5O12 thin films in spinel structure. Surface morphology and roughness values are analyzed using scanning electron microscope (FESEM) and atomic force microscope (AFM) images. The average work function value at room temperature is seen to be 5.2 eV. Cyclic voltammetry studies confirm the oxidation and reduction peaks appear at 1.58 V and 1.55 V respectively. Band edge parameters are calculated from the electrochemical data and band diagram for the Li4Ti5O12 thin film is established. Li ion dynamics is evaluated using electrochemical impedance spectroscopy data analyzed with equivalent circuit model. Conductivity values of Li4Ti5O12 thin films before and after the redox process is seen to be 1.25 × 10−6 and 1.36 × 10−6 S/cm respectively. Correlation between the surface properties, band edge parameters and the electrochemical process is established and the band diagram of Li4Ti5O12 thin film is proposed.