Preparation of Li4 / 3Ti5 / 3 O 4 Thin Film Electrodes by a PVP Sol-Gel Coating Method and Their Electrochemical Properties

Abstract

A 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 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 ion in the thin film electrode was estimated to be cm2 s−1 by using an impedance measurement at 1.59 V vs. The above results indicate that the 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.