Fabrication of Li2O-B2O3-P2O5 Solid Thin Film Electrolyte by Aerosol Flame Deposition

Abstract

Rechargeable thin film battery has various applications to electronic devices such as micro-electro-mechanical system, smart card, medical appliances, and so on. To realize the thin film battery, solid electrolyte with electrochemical stability and lithium ion mobility is indispensable and the necessity of solid electrolyte expedited the related researches during past tens of years. In this study, we employed the completely new method to synthesize the oxide glasses, which is called "Aerosol Flame Deposition (AFD)" method. The similar method was employed to produce the preform of optical fiber or optical waveguide devices based on oxide glasses applied to optical communication networks [1]. In the deposition process, single or multi-component amorphous oxide nano particles (soot) are synthesized by supplying metal halide sources such as chloride in the form of gas into oxy-hydrogen flame of ~1800°C. The deposited film composed of synthesized nano particles is subsequently consolidated into solid film by high temperature heat treatment. The whole processes are carried out under normal air atmosphere with only optional control for moisture. In the research, the aerosol flame deposition was applied to fabricate glass electrolyte film of Li2O-B2O3-P2O5 and analyzed for materials properties such as microstructure/morphology and the basic electrical property. To measure the ionic conductivities, Al/electrolyte/Al structures were fabricated on substrate. The 0.3 ?m thick aluminum electrodes were deposited by thermal evaporation. Conductivity was measured by complex impedance method using Solartron 1260 impedance analyzer and dielectric interface with an ac voltage of 50mV amplitude over the frequency range 1Hz to 1MHz at room temperatures.