Li-insertion into thin monolithic V2O5 films electrodes characterized by a variety of electroanalytical techniques

Slow-scan rate cyclic voltammetry (SSCV), potentiostatic intermittent titration (PITT) and electrochemical impedance spectroscopy (EIS) have been simultaneously applied to study Li-ion intercalation into V2O5 films prepared by vacuum-deposition on Pt foils. The most prominent feature of their electrochemical behavior relates to sharp minima on D versus E plots, which are observed in the vicinity of very narrow cyclic voltammetric peaks. This was explained in the framework of a lattice-gas model with very high, attractive electron-ion interactions during Li-ion intercalation into the V2O5 electrode, as was already described for similar processes in graphite and some transition metal oxides: LixCoO2, LixNiO2, LixCoyNi1−yO2 and LixMn2O4. Referring to the impedance spectra of the V2O5 electrodes, we show good agreement between the data obtained by the different techniques in the related time (or frequency) domains. This relates to both the differential intercalation capacity, Cint (low-frequency domain), and the chemical diffusion coefficient D (medium-frequency domain).