Direct Observation and Quantitative Analysis of Lithium Dendrite Growth by In Situ Transmission Electron Microscopy

Abstract

In this work, a unique in situ transmission electron microscopy technique (TEM) was developed to evaluate the mechanical stress imposed at the lithium metal and the electrolyte interface during lithium dendrite growth. The method enables a direct observation of the lithium deposition process and the quantification of the mechanical stress associated with the dendritic growth of lithium metal. We successfully observed a nano-sized lithium dendrite nucleation/growth and quantified its pushing force during the process. The transition of the growth mode from a vertical direction to a parallel direction (relative to the solid electrolyte surface) after the compressive stress reached a threshold value was observed. The transition stress was much lower than the yield stress of nano-sized lithium and the stiffness of the solid electrolyte. The fundamental information obtained by this work gives useful insight towards designing a robust solid electrolyte necessary for all-solid-state lithium batteries.