Property study of flexible lithium ion conducting thin films prepared by the RF magnetron sputtering method

Abstract

A flexible lithium ion conducting thin film with a unique chemical composition based on xLi2O–3GeO2–0.3MoO3 is deposited onto indium tin oxide (ITO)-coated polyimide (PI) substrates from their bulk glasses by the RF magnetron sputtering method. The lithium compositions of the bulk glasses and resultant films are measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The effect of the Li2O concentration on the microstructure of the LiGeMoO thin film electrolyte is investigated by XRD, FESEM and AFM. The Li2O concentration in the film electrolyte is found to affect the ion conductivity of the films. The ion conductivity of the film electrolyte can reach up to 1.13×10−6Scm−1 at x=2.5, with an activation energy of 0.55eV. The addition of Li2O not only increases the density of free interstitial lithium ions but also alters the network structure of the film, allowing more free volume for lithium drift and therefore increasing the ion conductivity of the film electrolyte. This structure variation as a function of the Li2O concentration is also observed by Raman spectroscopy.