Electrochemical and Raman studies on a hybrid organic-inorganic nanocomposite of vanadium oxide and a sulfonated polyaniline

The electrochemical and gravimetric behavior of a nanocomposite ([PSPAN](0. 3)V2O5. nH(2)O]) comprised of poly(N-propane sulfonic acid aniline) (PSPAN) and vanadium pentoxide xerogel are described. Electrochemical quartz cryst al microbalance (EQCM) measurements show that the charge compensation proce ss in this nanocomposite occurs predominantly by Li+ transport with a small amount of accompanying solvent, especially at low scan rates. The diffusio n coefficients for Li+ in both the vanadium pentoxide xerogel and in the na nocomposite are measured using the galvanostatic intermittent titration tec hnique (GITT), and a value of 1 x 10(-12) cm(2) s (-1) was determined for b oth materials. Combination of these results with electrochemical impedance spectroscopy (EIS) measurements shows that the nanocomposite is more electr onic conductor and exhibits shorter ionic diffusion pathways than the vanad ium pentoxide parent xerogel material. In situ Raman spectroscopic results on the nanocomposite unambiguously demonstrate the oxidation and reduction of the PSPAN component during redox cycling of the nanocomposite, even thou gh the electrochemical signature of the PSPAN is obscured by that of the va nadium pentoxide component. (C) 2001 Elsevier Science Ltd. All rights reser ved.