AVS 49th International Symposium
    Electrochemistry and Fluid-Solid Interfaces Monday Sessions
       Session EC+SS-MoA

Paper EC+SS-MoA7
Investigation of Binary Oxide (V@sub2@O@sub5@) Thin Films as Electrodes for Rechargeable Micro Batteries using Li

Monday, November 4, 2002, 4:00 pm, Room C-104

Session: Liquid-Solid Interfaces & Nanoscale Electrochemistry
Presenter: C. Benndorf, University of Hamburg, Germany
Authors: A. Talledo, Universidad Nacional de Ingenieria, Peru
H. Valdivis, Universidad Nacional de Ingenieria, Peru
C. Benndorf, University of Hamburg, Germany
Correspondent: Click to Email
We report on the preparation of V@sub2@O@sub5@ thin films, their charcetrization and their application as electrodes in rechargeable micro batteries using lithium as counter electrode. The V@sub2@O@sub5@ thin films were deposited onto SnO coated glass by reactive rf sputtering of a V cathode using an Ar + O@sub2@ atmosphere. The electrodes were characterized by their electrochemical behavior (IV-curves during charging and recharging using LiClO@sub4@ +PC as electrolyte), X-ray diffraction (XRD), X-ray and UV induced photoelectron spectroscopy (XPS and UPS) and infrared (IR) measurements. XRD measurements demonstrated that unannealed V@sub2@O@sub5@ films were amorphous with no sharp reflexes. Annealing to 350°C was sufficient to produce crystalline @beta@-V@sub2@O@sub5@. XPS spectra revealed the expected V/O ratio and the correct line positions. However, the O 1s peak was splitted into two components, one from the V@sub2@O@sub5@ component (530.8 eV). The other at 533.1 eV is attributed to the uptake of water from the atmosphere. The large uptake of water is consistent with a porous structure of the V@sub2@O@sub5@ thin film. The charged micro battery resulted in a maximum voltage of 3.4 V for the currentless circuit and a capacity of 34.5 mC/cm@super2@. With XPS we could demonstrate the migration of Sn into the V@sub2@O@sub5@ layer for the electrodes charged with Li. Further, UPS spectra from uncharged and charged V@sub2@O@sub5@ indicate a band gap narrowing due to the Li uptake, which is consistent with optical measurements. Our investigation contributes to the understanding and application of vanadium oxide thin films as cathodes for micro batteries.