New counter electrode prepared as vanadium oxide and V/Ce oxide films: preparation and characterization

Vanadium oxide and mixed V/Ce-oxide films at 78, 55, 38, 32 atomic % of V w ere prepared via the sol-gel route from an aqueous colloidal solution of in organic precursors. The influence of the added cerium precursor on their el ectrochemical, optical and structural properties was investigated by cyclic voltammetry (CV), X-ray analysis, LR spectroscopy and W-VIS techniques. Th e electrochemical stability of films was tested by CV measurements in 1 M L iClO4 in propylene carbonate electrolyte. The addition of CeO2 improved the poor stability of vanadium oxide films and enhanced their ion-charge capac ity up to 30 mC/cm2 for thicknesses about 300 nm. The intercalation of Liions in vanadium oxide and V/Ce-oxide films was followed by FT-IR spectrosc opy performed at near-grazing incidence angle (NGIA) conditions in combinat ion with CV measurements at potentials of - 1.5 V and + 2.0 V (vs. Ag/AgCl) . The observed shift of V-O-v vibrations in the IR spectra confirmed the in tercalation of Li+ ions. (C) 1999 Elsevier Science B.V. All rights reserved .