Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Standard electron microscopy struggles to preserve reactive battery materials post-operation.
• Cryogenic conditions maintain the native state of sensitive battery components.

Purpose of the Study:

• To atomically resolve lithium metal and its interface with the solid electrolyte interphase (SEI) using cryo-electron microscopy.
• To investigate the growth directions and crystallography of lithium dendrites.
• To characterize SEI nanostructures formed in various electrolytes.

Main Methods:

• Transmission electron microscopy at cryogenic temperatures.
• Atomic-resolution imaging of lithium metal and SEI.
• Analysis of crystallographic growth directions in lithium dendrites.

Main Results:

• Lithium metal dendrites grow as single-crystalline nanowires along specific crystallographic directions (<111>, <110>, <211>).
• Dendrite growth directions can shift at kinks without crystallographic defects.
• Distinct SEI nanostructures were observed depending on the electrolyte composition.

Conclusions:

• Cryogenic electron microscopy is essential for studying pristine battery materials.
• Understanding lithium dendrite growth and SEI formation is crucial for battery safety and performance.
• Tailoring electrolytes can influence SEI structure and potentially mitigate dendrite formation.