Characterization of Electrodeposited Li Metal by Cryo-Scanning Transmission Electron Microscopy/Electron Energy Loss Spectroscopy.

The Li metal anode is a promising key component for next-generation high-energy-density batteries. Understanding the charge/discharge mechanism of Li metal is therefore necessary for the effective utilization of Li metal anodes in commercial batteries. In this study, scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS) was conducted to reveal the chemical state of the Li metal anode surface. Cryogenic techniques and ultramicroelectrodes (UMEs) enabled the observation of electrodeposited Li metal on the nanometer scale. The chemical compositions of several surface layers were revealed by cryo-STEM-EELS analysis, and these measurements gave crucial information regarding the surface layer of the electrodeposited Li metal.