Characterizing the Li-Li7La3Zr2O12 interface stability and kinetics as a function of temperature and current density

The stability and kinetics of the Li-Li7La3Zr2O12 (LLZO) interface were characterized as a function of temperature and current density. Polycrystalline LLZO was densified using a rapid hot-pressing technique achieving 97.1 +/- 1% relative density, and <10% grain boundary resistance; effectively consisting of an ensemble of single LLZO crystals. It was determined that by heating to 175 degrees C, the room temperature Li-LIZO interface resistance decreases dramatically from 5822 (as-assembled) to 514 0 cm2; a > 10-fold decrease. In characterizing the maximum sustainable current density (or critical current density - CCD) of the Li-LLZO interface, several signs of degradation were observed. In DC cycling tests, significant deviation from Ohmic behavior was observed. In post-cycling tests, regions of metallic Li were observed; propagating parallel to the ionic current. For the cells cycled at 30, 70, 100, 130 and 160 degrees C, the CCD was determined to be 50, 200, 800, 3500, and 20000 mu A cm(-2), respectively. The relationships and phenomena observed in this work can be used to better understand the Li-LLZO interface stability, enabling the use of batteries employing Li metal anodes. (C) 2015 Elsevier B.V. All rights reserved.