Surface Superionic Conduction Enabled by In Situ Reaction-Constructed Li₂TiO₃@TiO₂ Core-Shell Interfaces for...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Ionics

Background:

• Insulating materials are critical for electron blocking in low-temperature solid oxide fuel cells (LT-SOFCs).
• Limited ion transport in insulators hinders electrochemical performance and causes cell failure.
• Developing efficient electrolytes for LT-SOFCs remains a significant challenge.

Purpose of the Study:

• To engineer an electrolyte with efficient ion-transport pathways for LT-SOFCs.
• To resolve cell failure issues associated with traditional insulator electrolytes.
• To enhance the electrochemical performance of solid oxide fuel cells at low temperatures.

Main Methods:

• In situ phase-transition strategy to create epitaxial core-shell structured electrolytes.
• Utilized LiOH-TiO2 precursor for spontaneous self-assembly of Li2TiO3@TiO2 core-shell architecture.
• Combined experimental characterizations with density functional theory (DFT) calculations.

Main Results:

• Successfully constructed Li2TiO3@TiO2 core-shell electrolyte with a surface superionic conductive layer.
• Established continuous 3D fast-ion transport pathways along interfacial regions.
• Achieved high ion conductivity (0.223 S/cm) and peak power density (759 mW/cm2) at 550°C.
• Demonstrated effective power output (189 mW/cm2) at a low temperature of 390°C.
• DFT calculations revealed enhanced charge transfer kinetics via synergistic interfacial effects.

Conclusions:

• The in situ phase-transition induced core-shell structure strategy effectively creates surface superionic conduction.
• This approach fundamentally resolves cell failure problems in insulator electrolytes for LT-SOFCs.
• The developed electrolyte offers new opportunities for high-performance solid-state ion devices operating at low temperatures.