Charge storage capability in nanoarchitectures of V2O5/chitosan/poly (ethylene oxide) produced using the layer-by-layer technique

The electrochemical and electrochromic properties of layer-to-layer nanoarchitectures of V2O5/chitosan and V2O5 alernated with a blend of poly(ethylene oxide) (PEO) and chitosan have been examined. Using a blend was important, since multilayers of PEO/V2O5 could not be built. The number of electrochemically active V2O5 sites was estimated to be around 3.4 x 10(-8) mol cm(-2) and 4.4 x 10(-8) mol cm(-2) for V2O5/chitosan and V2O5/blend, respectively, based on the UV-vis absorbance attributed to the intervalence V4+ --> V5+ transfer. A pronounced effect from PEO was observed in the migration/diffusion process, according to cyclic voltammetry and impedence spectroscopy data. The charges infected were 3.29 mC cm(-2) and 8.02 mC cm(-2) for V2O5/chitosan and V2O5/blend, respectively, at 20 mV s(-1). For V2O5/blend, the chronopotentiometric curves show that x in LixV2O5 is about 1.77. Evidence of enhanced ionic transport was provided by the Fourier transform infrared (FTIR) spectrum, which indicated lithium complexation by PEO and formation of a larger amorphous phase of PEO within the V2O5 matrix. The importance of these results for the production of Li secondary microbatteries and electrochromide devices is discussed.