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‐by‐layer nanoarchitectures of V₂O₅/chitosan and V₂O₅ alternated 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 × 10^–8 mol cm^–2 and 4.4 × 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 impedance spectroscopy data. The charges injected 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 Li_xV₂O₅ 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 electrochromic devices is discussed.