Trapping and imaging dynamic battery nanointerfaces via electrified cryo-EM.

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• The electrified interface between liquid and solid phases is crucial for batteries and biological systems.
• Conventional tools cannot capture the nanoscale dynamics of this metastable interface.
• Understanding the solid electrolyte interphase (SEI) is key to battery performance.

Purpose of the Study:

• To characterize the nanoscale dynamics of the electrified interface during battery operation.
• To quantify the early-stage growth kinetics of the solid electrolyte interphase (SEI).
• To elucidate the factors governing the performance of different SEI chemistries.

Main Methods:

• Utilizing electrified cryo-electron microscopy (eCryo-EM) to rapidly freeze and capture dynamic, nonequilibrium interfacial states.
• Analyzing collective snapshots of the electrified interface at controlled time intervals.
• Quantifying SEI growth kinetics under diffusion-limited and reaction-limited regimes.

Main Results:

• The diffusivity of charged species in two SEI films with different chemistries was found to be similar (within 10%).
• The reaction-limited SEI growth regimes differed by a factor of 3 between the two SEI films.
• Lowered reactivity of the high-performance electrolyte was identified as the primary reason for its high coulombic efficiency.

Conclusions:

• Electrified cryo-electron microscopy (eCryo-EM) provides unprecedented nanoscale insights into SEI formation.
• SEI performance is primarily dictated by its reactivity rather than ion diffusivity.
• This work offers a new method for understanding and optimizing battery interfaces.