Lithium electroinsertion into an inorganic-organic hybrid material composed from V2O5 and polyaniline

Composites of V2O5 xerogel with polyaniline (PANI) are prepared from a vanadyl tris(isopropoxide) precursor and aniline monomer by in situ oxidative polymerization of aniline in the sol solution, followed by gelation with the inorganic oxide. The composite is characterized using Fourier transform infrared spectroscopy, X-ray diffraction, electroacoustic impedance, electrochemical quartz crystal microbalance (EQCM), electrochemical impedance, in situ resistance, cyclic voltammetry, UV-visible (UV-vis) spectroscopy, and multiple charge/discharge measurements. Electrochemical impedance data at -0.7 V give a value for the Li+ diffusion coefficient in the composite of 2x10(-11) cm(2) s(-1), in contrast to the value of 3x10(-12) cm(2) s(-1) obtained for V2O5. EQCM data show that charge compensation in the composite is achieved predominantly by Li+ electromigration, as is also the case for V2O5. In situ resistance measurements reveal that the composite has a very high conductivity over the potential range 0.4 to -0.5 V. In contrast, V2O5 exhibits much lower conductivity over this range and also shows a deep minimum in conductivity near -0.2 V. Both materials become more resistive at potentials more negative than -0.5 V. UV-vis spectroscopy of the materials reveals changes in the optical bandgap that are consistent with these resistance changes. Finally, the composite shows excellent stability toward repeated charge/discharge cycling. (C) 2002 The Electrochemical Society.