Direct Observation of a Li-Ionic Space-Charge Layer Formed at an Electrode/Solid-Electrolyte Interface

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Physics

Background:

• Mobile charge carriers redistribute at interfaces between different materials due to potential differences.
• This charge redistribution significantly impacts ion conduction across interfaces, particularly between electrodes and solid electrolytes.
• Understanding ionic carrier distribution and potential is crucial for enhancing interfacial ion transport.

Purpose of the Study:

• To visualize the ionic and potential profiles within the space-charge layer (SCL) at the interface between a copper electrode and a lithium-conductive solid electrolyte.
• To investigate the role of charge redistribution in interfacial phenomena relevant to electrochemical devices.

Main Methods:

• Utilized phase-shifting electron holography for visualization.
• Employed spatially resolved electron energy-loss spectroscopy for detailed analysis.
• Focused on electron microscopy techniques to probe the nanoscale interface.

Main Results:

• Successfully visualized the Li-ionic space-charge layer (SCL) at the Cu/solid electrolyte interface.
• Observed a significant potential drop of 1.3 V within 10 nm of the interface.
• Demonstrated the capability of the applied electron microscopy techniques to map ionic and potential distributions.

Conclusions:

• The study provides direct visualization of the ionic and potential profiles in the SCL.
• These findings offer critical insights into interfacial charge transport mechanisms.
• The applied techniques hold potential for advancing the development of next-generation electrochemical devices, such as solid-state batteries.