The Effect of Temperature and Al as an Additive on the Synthesis, Structure, Densification, and Conductivity of Garnet-Type Li7La3Zr2O12

Garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes are promising candidates for application in next-generation solid-state batteries. Of note, the most controversial issue is to stabilize the cubic phase structure (c-LLZO) with high density after the sinter process to reach high ionic conductivity with the desired strength. Considering this issue, the current study aims to investigate the synthesis and sintering of LLZO with Al substituted and without any additive. The LLZO ceramic was synthesized through conventional solid-state reaction. The effect of heating temperature on the synthesis of the cubic structure was studied using X-Ray Diffraction (XRD). The ionic conductivity of the samples was examined by AC Impedance Spectroscopy. The obtained results indicated that Al doping led to the cubic phase stabilization and that it had a positive effect on the sintering regime so that the sample with Al dopant was densified at the lower temperature of 1140 °C. The total ion conductivity of Al-LLZO is 0.1 mScm-1 which is comparable to the values of high temperature-sintered samples.