Evaluation of fundamental transport properties of Li-excess garnet-type Li5+2xLa3Ta2−xYxO12 (x = 0.25, 0.5 and 0.75) electrolytes using AC impedance and dielectric spectroscopy

摘要: The fundamental electrical transport properties including ionic conductivity, dielectric constants, loss tangent, and relaxation time constants of Li-excess garnet-type cubic (space group Iad) Li5+2xLa3Ta2−xYxO12 (x = 0.25, 0.5 0.75) have been studied in the temperature range −50 to 50 °C using electrochemical AC impedance spectroscopy. A correlation has established between excess Li content Li+ ion migration pathways. tangent (tan δ) for all samples exhibits a peak corresponding because dipolar rotations due migration. Comparing modulus analysis garnets with fluorite-type oxygen conductors, we propose local ions octahedral sites around “immobile” tetrahedral (24d) sites. In x 0.25 0.5, seem jump from one (96h) site another bypassing them (path A), both long-range order processes, activation energies ∼0.69 0.54 eV, respectively. For 0.75 member, exhibit mainly migration, an energy 0.34 where hopping two occurs through edge which is shared LiO6 octahedra LiO4 tetrahedron B). present consistent ab initio theoretical that showed conduction paths (A B) different energies.