Optimizing Li+ conductivity in a garnet framework

The garnet-related oxides with the general formula Li7-xLa3Zr2-xTaxO12 (0 < x < 1) were prepared by conventional solid-state reaction. X-ray diffraction (XRD), neutron diffraction and AC impedance were used to determine phase formation and the lithium-ion conductivity. The lattice parameter of Li7-xLa3Zr2-xTaxO12 decreased linearly with increasing x. Optimum Li-ion conductivity in the Li-ion garnets Li7-xLa3Zr2-xTaxO12 is found in the range 0.4 <= x <= 0.6 for samples fired at 1140 degrees C in an alumina crucible. A room-temperature sigma(Li) approximate to 1.0 x 10 (3) S cm (1) for x = 0.6 with an activation energy of 0.35 eV in the temperature range of 298-430 K makes this Li-ion solid electrolyte attractive for a new family of Li-ion rechargeable batteries.