THE INFLUENCE OF INTERCALATED IONS ON CYCLIC STABILITY OF V2O5/GRAPHITE COMPOSITE IN AQUEOUS ELECTROLYTIC SOLUTIONS: EXPERIMENTAL AND THEORETICAL APPROACH

An amorphous V2O5 xerogel/graphite composite was synthesized and subjected to electrochemical characterization by cyclic voltammetry, chronopotentiometry and impedance measurements in aqueous LiNO3, NaNO3, KNO3 and Mg(NO3)(2) solutions. The kinetics of cyclic intercalation/deintercalation reactions, and the dependence of coulombic capacity on cycle number were examined. The capacity retention depended on the type of inserted ions and decreased in the following order: Mg2+ > Li+ > Na+ > K+. By ultraviolet/visible (UV/VIS) spectroscopy the concentration of dissolved vanadium oxide was determined and correlated with the capacity fade in various electrolyte solutions. By means of Density Functional Theory calculation (DFT), the bond strength between vanadium and triple coordinated oxygen in V2O5 was found to be responsible for the differences in its solubility in various aqueous solutions. (C) 2015 Elsevier Ltd. All rights reserved.