In situ observation of cracking and self-healing of solid electrolyte interphases during lithium deposition

The growth of lithium (Li) whiskers is detrimental to Li batteries. However, it remains a challenge to directly track Li whisker growth. Here we report in situ observations of electrochemically induced Li deposition under a CO2 atmosphere inside an environmental transmission electron microscope. We find that the morphology of individual Li deposits is strongly influenced by the competing processes of cracking and self-healing of the solid electrolyte interphase (SEI). When cracking overwhelms self-healing, the directional growth of Li whiskers predominates. In contrast, when self-healing dominates over cracking, the isotropic growth of round Li particles prevails. The Li deposition rate and SEI constituent can be tuned to control the Li morphologies. We reveal a new weak-spot mode of Li dendrite growth, which is attributed to the operation of the Bardeen-Herring growth mechanism in the whisker's cross section. This work has implications for the control of Li dendrite growth in Li batteries. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

This study provides in situ observations of electrochemically induced Li deposition under a CO2 atmosphere, revealing the influence of cracking and self-healing of the solid electrolyte interphase (SEI) on the morphology of individual Li deposits. The relative balance between cracking and self-healing can be tuned to control the morphology of Li deposits, thereby affecting the growth of Li whiskers and the strength of Li dendrites.