Effect of Li2O on devitrification and conductivity of MgO–V2O5 for energy storage

Abstract

The composition of 75V2O5–(25-x) MgO–xLi2O (x = 0, 1.5, 3.0, 4.5, and 6.0) is synthesized by the melt quenching method. The effects of Li2O on devitrification, physical, thermal, structural, and conducting properties of the as-quenched samples are analyzed utilizing various experimental techniques. X-ray diffraction and differential thermal analysis confirmed the formation of phase-separated glasses up to 3.0 mol. % of Li2O. Above this concentration of Li2O, the samples are glass ceramic. With an increase in the concentration of Li2O, the density increases in all the samples. The Raman spectra demonstrate that as the concentration of Li2O increases, there is a transition of VO5 units into different structural units of vanadium oxide. The highest conductivity is observed for the composition with x = 4.5, i.e., 10−4 S/cm at 250 °C. The activation energy indicated that the present samples could be mixed conductors in nature. These samples can be used as cathode materials in energy storage devices due to their mixed conduction with an appropriate conductivity at 250 °C.