Observation of Fast Low-Temperature Oxygen Ion Conduction in CeO₂/β"-Al₂O₃ Heterostructure.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Semiconductor ion fuel cells (SIFCs) show promise for efficient power generation below 600°C.
• Understanding ionic conduction mechanisms in composite electrolytes is crucial for low-temperature SIFC operation.
• Current limitations include cell failure below 419°C due to inadequate ionic transport.

Purpose of the Study:

• To develop a novel composite electrolyte for enhanced low-temperature performance in SIFCs.
• To investigate the role of local electric fields and modified melting points in ionic conduction.
• To overcome the operational temperature limitations and cell failure issues in SIFCs.

Main Methods:

• Introduction of a CeO2/β″-Al2O3 heterostructure electrolyte.
• Leveraging the local electric field (LEF) effect within the heterostructure.
• Manipulation of carbonate/hydroxide (C/H) melting points using Na+ and Mg2+ ions from β″-Al2O3.

Main Results:

• Achieved ionic conductivity of 0.019 S/cm and power output of 85.9 mW/cm² at 350°C.
• Demonstrated peak power density of 1 W/cm² with ionic conductivity of 0.197 S/cm at 550°C.
• Successfully enabled oxygen ion transport at 350°C, preventing cell failure below 419°C.

Conclusions:

• The engineered CeO2/β″-Al2O3 heterostructure effectively facilitates low-temperature oxygen ion transport.
• Engineering the LEF and incorporating lower melting point C/H are viable strategies for high-performance SIFCs.
• This approach offers a promising pathway for developing advanced SIFCs operating between 300-600°C.