Decoupling electrochemical reaction and diffusion processes in ionically-conductive solids on the nanometer scale.

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Understanding ion dynamics is crucial for energy storage devices.
• Existing methods struggle to decouple ion transport from local reactivity at the nanoscale.

Purpose of the Study:

• To develop a nanoscale imaging technique for voltage-controlled ion dynamics.
• To differentiate between ion transport and local electrochemical reactions in conductive solids.

Main Methods:

• Electrochemical strain microscopy (ESM) utilizing dynamic local strain (0.1-1 MHz).
• Spectroscopic modes with low-frequency (∼1 Hz) voltage sweeps.
• First-order reversal curve (FORC) measurements to analyze bias-dependent hysteretic strain response.

Main Results:

• ESM successfully detects bias-induced ionic motion via local strain.
• FORC analysis reveals a critical voltage for ion activation and linear behavior above it.
• The method effectively separates local electrochemical reaction and transport processes.

Conclusions:

• The developed ESM approach allows for nanoscale mapping of ion dynamics and reactivity.
• Key parameters like critical voltage and effective mobility can be extracted locally.
• The technique shows promise for analyzing amorphous Si anodes in Li-ion batteries and other ionically conductive systems.