Characterization of vanadium oxide and new v/ce oxide films prepared by sol-gel process

Abstract

The preparation of vanadium oxide and new mixed V/Ce oxide thin films as intercalation compound for lithium ions (at 55 and 38 at. % of V) started from aqueous inorganic precursors. Thin films were prepared via the sol-gel process by dip-coating only once. Glass slides covered with SnO 2:F were used as substrates. The influence of added cerium precursors on the electrochemical optical and structural properties of thin films was studied by cycling voltammetry (CV), in-situ ultraviolet and visible (UV-VIS) spectroscopy, atomic force microscopy (AFM) and IR spectroscopy. The addition of CeO 2 improved the poor stability of vanadium oxide films and enhanced their ion-charge capacity up to 30 mC/cm 2. In all films the process of intercalation of lithium ions was followed by in-situ UV-VIS spectroscopy and ex-situ FT-IR spectroscopy performed at near-grazing incidence angle. The intercalation of Li + ions was confirmed trough shifting of the absorbance edge in UV-VIS spectra and by the observed shifts of V-O v vibrations in the IR spectra. The surface of the films was also characterized by AFM imaging before and after cycling in 1M LiClO 4 in propylene carbonate electrolyte.