Enhancement in conductivity by K2O in MgO-V2O5 glass-ceramic for solid- state battery application

Composition of 75V(2)O(5)-(25-x) MgO-(x) K2O (x = 6, 9, 12, and 15 mol%) are synthesized by melt quench technique. All the as quenched samples either formed the glasses or glass ceramic as confirmed by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The DSC curves exhibited the two glass transition temperatures (T-g), two crystallization temperatures (T-c)(,) and with two melting temperatures (T-m) which could be related to the presence of two distinct glass in the present samples. The K2O content increases the devitrification tendency of as quenched samples and formed the crystalline phases i.e. K3VO4 along with glassy phase in higher concentration of K2O. X-ray photoelectron spectroscopy (XPS) is confirmed that the vanadium exhibit two oxidation states V4+ / V5+. The highest ratio of V4+/V5+ is found in (x = 15) sample which exhibited the highest conductivity i.e. 1.3 x 10(-3) S/cm at 250 degrees C. It is two orders higher than the (x = 6) sample at 250 degrees C. The high conducting glass ceramics can be used as cathode in all solid state battery and fuel cells.