Preparation of Li[sub 4/3]Ti[sub 5/3]O[sub 4] Thin Film Electrodes by a PVP Sol-Gel Coating Method and Their Electrochemical Properties

Abstract

A Li4/3Ti5/3O4Li4/3Ti5/3O4 thin film electrode for rechargeable lithium batteries was prepared by a sol-gel coating method with poly(vinylpyrrolidone) (PVP). A Li-Ti-O sol was successfully prepared by using PVP. The sol coated on Au substrate with a spin coater was converted to a gel film through a spin coating process. The Li-Ti-O gel film was heated at various temperatures for 1 h. The prepared thin films were characterized with both X-ray diffraction method and scanning electron microscopy. These analyses indicated that the prepared film belonged to a spinel structure and had a uniform morphology. Electrochemical properties of the prepared electrode films were evaluated by using a discharge and charge test, cyclic voltammogram, and impedance spectroscopy in a mixed solvent of ethylene carbonate and diethyl carbonate (1:1 in volume) with 1.0 mol dm⁻³ LiClO4.LiClO4. From these results, it can be said that the thin film electrode prepared at 600°C for 1 h had excellent electrochemical properties. A chemical diffusion coefficient of Li+Li+ ion in the Li4/3Ti5/3O4Li4/3Ti5/3O4 thin film electrode was estimated to be 2.1×10−92.1×10−9 cm² s⁻¹ by using an impedance measurement at 1.59 V vs. Li/Li+.Li/Li+. The above results indicate that the Li4/3Ti5/3O4Li4/3Ti5/3O4 film prepared through the sol-gel coating method with PVP can be used as an anode with a fast electrochemical response for rechargeable lithium batteries. © 2003 The Electrochemical Society. All rights reserved.