Microstructure and Li-Ion Conductivity of Hot- Pressed Cubic Li7La3Zr2O12

The effect of hot-pressing temperature on the microstructure and Li-ion transport of Al-doped, cubic Li7La3Zr2O12 (LLZO) was investigated. At fixed pressure (62MPa), the relative density was 86%, 97%, and 99% when hot-pressing at 900 degrees C, 1000 degrees C, and 1100 degrees C, respectively. Electrochemical impedance spectroscopy showed that the percent grain-boundary resistance decreased with increasing hot-pressing temperature. Hot pressing at 1100 degrees C resulted in a total conductivity of 0.37mS/cm at room temperature where the grain boundaries contributed to 8% of the total resistance; one of the lowest grain-boundary resistances reported. We believe hot pressing is an appealing technique to minimize grain-boundary resistance and enable correlations between LLZO composition and bulk ionic conductivity.