Crystal structure of cubic Li7-3xGaxLa3Zr2O12 with space group of I-43d

Abstract

Cubic Li7-3xGaxLa3Zr2O12 is a cubic phase with a space group of I-43d instead of Ia-3d. This structure is more conducive to the migration of lithium ions. However, the effect of Ga on the size and environment of lithium ion transport channels has not been researched. In this work, Li7-3xGaxLa3Zr2O12 (x = 0–0.25) was formulated, and the crystal structure was obtained by neutron diffraction. The results indicated that the minimum channel size to control Li+ migration in LLZO was the bottleneck size between the Li2 and Li3 sites (bottleneck size 2), and compared with lanthanum ions, the zirconium ions were closer to lithium ions. As the Ga content increased, bottleneck size 2 levelled off, while the lithium concentration and the distance between skeleton ions and lithium ions decreased. As a result, the lithium ionic conductivity primarily increased and then decreased. When doping 0.2 pfu of Ga, LLZO exhibited the highest lithium ionic conductivity of 1.45 mS/cm at 25 °C due to the coordinated regulation of Li+ concentration, bottleneck size, and the distance between skeleton ions and lithium ions.