Electrical and dielectric enhancements in lithium-ion doped vanadium-zinc-phosphate glass for energy storage applications

Glass samples with the compositional range xLi2O-(1-x)[0.45V2O5-0.25ZnO-0.30P2O5] (LVZP) (x = 0.10, 0.15, 0.20, and 0.25) were synthesized using the melt-quench method to investigate the influence of lithium-ion doping on their electrical and dielectric properties. The density and molar volumes of these glasses were measured using Archimedes' principle, revealing that increasing Li2O content decreases the density, suggesting increased free volume and structural modifications. Increments in the molar volume were attributed to an increase in non-bridging oxygens that weaken the glassy network and enhance electrical conductivity. Electrical properties were thoroughly investigated using impedance spectroscopy at temperatures ranging from 373K to 513K and frequencies between 40 Hz and 5 MHz. Key properties like impedance, conductivity, density of states at the Fermi level N(EF), and enthalpy values were extracted using a variety of models, such as the correlated barrier hopping (CBH) model, the Almond-West formalism, and Nyquist plot analysis. The CBH model states that the parameter 's' decreases as temperature rises, suggesting AC conduction through small polaron hopping. Bergman's model has been employed for the dielectric studies. The structure and temperature-dependent relaxation mechanisms of charge carriers were examined using modulus scaling. Results demonstrate that controlled inclusion of lithium-ion upsurges ionic and electronic conductivity, highlighting their potential use in energy storage devices, particularly as electrode materials.