Fe-containing CeVO sub(4) films as Li intercalation transparent counter-electrodes

• Published in: Electrochimica acta 2001-04, Vol.46 (13-14), p.2077-2084
• Main Authors: Artuso, F, Picardi, G, Bonino, F, Decker, F, Bencic, S, Surca Vuk, A, Opara Krasovec, U, Orel, B
• Format: Article
• Language: English
• ISSN: 0013-4686

Iron containing CeVO sub(4) films were prepared using the sol-gel method. The crystalline structure of powders and films with Fe/Ce/V ratios of 0.1:1:1, 0.3:1:1 and 0.5:1:1 were investigated by X-ray diffraction (XRD) and infrared (IR) spectroscopy. XRD revealed the predominance of a CeVO sub(4)-W (wakefieldite) crystalline phase with a small amount of monoclinic CeVO sub(4), CeO sub(2) and Fe sub(2)O sub(3). Ex situ IR absorbance spectra of charged and discharged films show the changes in intensity of the V-O stretching mode at 770 cm super(-1). Cyclic voltammetry showed that Li super(+) intercalation occurs in three steps with total capacities of 22 mCcm super(-2) (Fe/Ce = 0.1), 32 mCcm super(-2 ) (Fe/Ce = 0.3) and 37 mCcm super(-2) (Fe/Ce = 0.5). The increase in the overall charge capacity with increasing Fe content is accompanied by a loss of capacity with cycling. The lithium diffusion coefficient, calculated by the galvanostatic intermittent titration method (GITT), the potentiostatic intermittent titration method (PITT) and electrochemical impedance spectroscopy (EIS), ranges from 10 super(-12) to 10 super(-14) cm super(2)s super(-1). UV-vis in situ transmittance spectra showed that these films are highly transparent with a photopic transmittance T sub(Vis)[similar to]0.85 for intercalated and deintercalated states. This suggests that Fe /Ce/V oxide films are good candidates for optically passive counter-electrodes in electrochromic (EC) devices. copyright 2001 Elsevier Science Ltd.