FABRICATION OF LIV2O5 THIN-FILM ELECTRODES FOR RECHARGEABLE LITHIUM BATTERIES

LiV2O5 thin-film electrodes have been prepared for the first time by u sing the plasma enhanced chemical vapor deposition (PECVD) technique. A novel lithium precursor, lithium hexafluoroisopropoxide ((CF3)(2)CHO Li), has been synthesized to take advantage of its low sublimation tem perature (similar to 50 degrees C). Vanadium oxytrichloride (VOCl3) is used as the vanadium precursor. These two precursors are introduced i nto the plasma chamber by using argon as the carrier gas. Hydrogen and oxygen gases are also introduced into the chamber to facilitate the r eactions. The gas compositions in the chamber and other deposition con ditions have been optimized to obtain LiV2O5 films. The structure and electrochemical properties of the films depend strongly on the substra te temperature and deposition power. The optimized substrate temperatu re and radiofrequency (RF) power are 250 degrees C and 50 W, respectiv ely. The charge capacity of the film is approximately 300 mA/h/cm(3), with two plateaus at 3.5-3.6 V on the discharge profile. The films can be cycled reversibly in the range of 0 <x < 1 (in LixV2O5)for 2000 cy cles with a capacity loss of 0.0076% per cycle and are good candidates for use as the cathode in thin-film lithium ion batteries. (C) 1998 E lsevier Science B.V. All rights reserved.