Electrochemical Stability of Garnet-Type Li7La2.75Ca0.25Zr1.75Nb0.25O12 with and without Atomic Layer Deposited-Al2O3 under CO2 and Humidity

Interest toward developing all-solid-state batteries incorporating lithium-stuffed garnet electrolytes (LSGEs) has been on the constant rise. However, LSGEs are known to react with humidity, and subsequently, CO2 during preparation or storage, leading to Li2CO3 formation. In this study, we report the long-term exposure effects of CO2 and humidity on the lithium-ion conductivity of typical garnet-type Li7La2.75Ca0.25Zr1.75Nb0.25O12 with and without Al2O3 deposited by atomic layer deposition (ALD). The ionic conductivity of the samples was investigated by electrochemical impedance spectroscopy as a function of time for up to 1000 h. The impedance spectra of ALD-coated garnet-type Li7La2.75Ca0.25Zr1.75Nb0.25O12 sample was unaffected by long-term exposure to 400 ppm up to pure CO2 while the uncoated garnet-type sample show at least 8% increase in total resistance. Both samples show increased resistance in the presence of humidity, but the resistance recovers upon removal of the humidity. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org.