In Operando TEM Investigation of All-Solid-State Garnet-Based Lithium Batteries

Li₇La₃Zr₂O₁₂ (LLZO)-based all-solid-state Li batteries (SSLBs) are very attractive next-generation energy storage devices owing to their potential for achieving enhanced safety and improved energy density. However, the rigid nature of the ceramics challenges the SSLB fabrication and the afterward interfacial stability during electrochemical cycling. To reveal the degradation mechanism of the LLZO based SSLB, a collaboration between IEK-9, Forschungszentrum Jülich, and National Yang Ming Chiao Tung University, Taiwan, by using in operando transmission electron microscopy (TEM) was carried out to understand the SSLB system on an atomic scale level. In the publication, a promising LLZO-based SSLB with a high areal capacity and stable cycle performance over 100 cycles is demonstrated. In operando TEM is used for successfully demonstrating and investigating the delithiation/lithiation process and understanding the capacity degradation mechanism of the SSLB. Other than the interfacial delamination between LLZO and LiCoO₂ (LCO) owing to the stress evolvement during electrochemical cycling, oxygen deficiency of LCO not only causes microcrack formation in LCO but also partially decomposes LCO into metallic Co and is suggested to contribute to the capacity degradation based on the atomic-scale insights. When discharging the SSLB to a voltage of ≈1.2 versus Li/Li⁺, severe capacity fading from the irreversible decomposition of LCO into metallic Co and Li₂O is observed under in operando TEM. These observations reveal the capacity degradation mechanisms of the LLZO-based SSLB, which provides important information for future LLZO-based SSLB developments. The publication was published in Advanced Science with open access entitled “All-Solid-State Garnet-Based Lithium Batteries at Work – In Operando TEM Investigations of Delithiation/Lithiation Process and Capacity Degradation Mechanism“, which can be viewed at

Published: 2022/12/18

https://onlinelibrary.wiley.com/doi/full/10.1002/advs.202205012