The effect of two different substituted atoms in lithium positions on the structure of garnet-type solid electrolytes

Li${}_{7}$La${}_{3}$Zr${}_{2}$O${}_{12}$ (LLZO), lithium lanthanum zirconate is a promising garnet-type solid electrolyte that is being intensively studied for solid-state lithium batteries. The properties of LLZO such as compatibility with the lithium electrode, stability, and ionic conductivity make them to be used in all solid-state batteries. Moreover, lithium ion concentration and distribution, doping different cations, chemical composition, and interaction between different dopants have remarkable effects on the ionic conduction of LLZO material. Herein, we investigate the solid electrolyte, Li${}_{6.4}$(Ga${}_{(1-y)}$In${}_{(y)}$)${}_{0.2}$La${}_{3}$Zr${}_{2}$O${}_{12}$ (y = 0.05, 0.10, 0.15, 0.20), by probing the influence of indium substitution to gallium sites at the same lithium concentration on the structure and the lithium ion conduction. A conventional solid state route, ball milling was used to synthesize the materials. Crystal structure, morphology, ionic conduction, and local electronic structure were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and X-ray absorption fine structure (XAFS) techniques, respectively. The results revealed that the existence of indium effected the conduction adversely, although made no significant changes on the local structure.