Cryo-STEM mapping of solid-liquid interfaces and dendrites in lithium-metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Solid-liquid interfaces are crucial in various processes but challenging to characterize at high resolution.
• Understanding dendritic deposition and solid-electrolyte interphase formation is vital for lithium-metal battery safety and performance.
• Previous methods lacked the capability to observe these interfaces in their native state.

Purpose of the Study:

• To adapt cryo-transmission electron microscopy (cryo-TEM) for studying solid-liquid interfaces in lithium-metal batteries.
• To enable structural and chemical mapping of these interfaces using cryo-scanning transmission electron microscopy (cryo-STEM).
• To investigate the coexistence and characteristics of dendrite types on lithium anodes.

Main Methods:

• Vitrification of liquid electrolytes to preserve native states of solid-liquid interfaces.
• Application of cryo-transmission electron microscopy (cryo-TEM) for hydrated specimen analysis.
• Utilizing cryo-scanning transmission electron microscopy (cryo-STEM) for structural and chemical mapping.

Main Results:

• Identification of two distinct types of dendrites coexisting on the lithium anode.
• One dendrite type exhibits an extended solid-electrolyte interphase layer.
• The other dendrite type unexpectedly consists of lithium hydride, potentially causing significant capacity loss.

Conclusions:

• Cryogenic electron microscopy is a powerful technique for probing nanoscale processes at intact solid-liquid interfaces.
• The findings provide crucial insights into lithium dendrite formation mechanisms in batteries.
• The discovery of lithium hydride dendrites offers new perspectives on battery degradation and performance limitations.