Structural, Morphological and Electrical Characteristics of Sol-Gel Prepared Lithium Triflate - Alumina Composite Electrolyte

Abstract

The objective of this work is to study the structural, morphological and electrical characteristics of lithium triflate-alumina composite electrolytes which were prepared via sol-gel technique. For this purpose, the composite electrolyte pallet samples which were sintered at 300 °C for four hours were subjected to X-ray diffraction, scanning electron microscopy, impedance spectroscopy and transference number measurement. X-ray diffraction spectra and scanning electron micrographs indicated that the crystalline alumina was distributed over the amorphous lithium triflate phase implying that the two-phases of microstructure (lithium triflate and alumina) interspersed each other. The highest ionic conductivity of 2.86 × 10-3 S cm-1 at room temperature was obtained for the sample with 60 mol % alumina. Temperature dependence of conductivity study was performed in the 303 K to 423 K temperature range and the trend of conductivity-temperature plot suggested that the increase in conductivity was due to the increase in migration rate of ions with temperature. The non-Arrhenius plot of the conductivity-temperature was due to continuous freezing of cations within the amorphous triflate medium. The value of ionic transference number indicated that the majority charge carriers in this composite electrolyte were ions while the value of Li+ transference number suggested that the majority of the ions were anions.