Early Stage Li Plating by Liquid Phase and Cryogenic Transmission Electron Microscopy
Hayoung Park, Yonggoon Jeon, Woo Jun Chung, Yuna Bae, Jihoon Kim, Hayeon Baek, Jungwon Park
Abstract
Li metal anodes are among the most promising options for next-generation batteries, exhibiting the highest theoretical capacity. However, irregular Li electrodeposition, which raises safety concerns, is a major obstacle in practical applications. Therefore, a fundamental understanding of the beginning phases of Li plating, such as nucleation and early growth, which have a decisive influence on the dendritic growth of Li, is essential. In this study, we investigated the early stage of Li plating at the single-particle level and its correlation with the solid-electrolyte interphase (SEI) using in situ liquid phase transmission electron microscopy (TEM) and cryogenic TEM. We observed contrasting nucleation dynamics and particle growth patterns in two electrolytes (1 M LiPF6 in ethylene carbonate/diethyl carbonate and 1 M LiTFSI in 1,3-dioxolane/dimethoxy ethane), which originate from different chemical and physical properties of the SEIs. Based on our findings, we propose a mechanism of nucleation and initial growth of Li dictated by the SEI.