Fabrication of LiV2O5 Thin-Film Electrodes for Rechargeable Lithium Batteries

LiV₂O₅ thin-film electrodes have been prepared for the first time by using the plasma enhanced chemical vapor deposition (PECVD) technique. A novel lithium precursor, lithium hexafluoroisopropoxide ((CF₃)₂CHOLi), has been synthesized to take advantage of its low sublimation temperature (∼ 50°C). Vanadium oxytrichloride (VOCl₃) is used as the vanadium precursor. These two precursors are introduced into the plasma chamber by using argon as the carrier gas. Hydrogen and oxygen gases are also introduced into the chamber to facilitate the reactions. The gas compositions in the chamber and other deposition conditions have been optimized to obtain LiV₂O₅ films. The structure and electrochemical properties of the films depend strongly on the substrate temperature and deposition power. The optimized substrate temperature and radiofrequency (RF) power are 250°C and 50 W, respectively. The charge capacity of the film is approximately 300 mA/h/cm³, 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 Li_xV₂O₅) for 2000 cycles with a capacity loss of 0.0076% per cycle and are good candidates for use as the cathode in thin-film lithium ion batteries.