Advanced Fuel Cell Based on New Nanocrystalline Structure Gd_0.1Ce_0.9O₂ Electrolyte.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Developing low-temperature solid oxide fuel cells (<600 °C) is crucial for commercialization.
• Traditional solid oxide fuel cell (SOFC) electrolytes rely on bulk diffusion, limited by density and temperature.
• Improving ionic conductivity in electrolytes is a key research and development challenge.

Purpose of the Study:

• To investigate a novel conduction mechanism in nanocrystalline cerium gadolinium oxide (GDC) electrolytes.
• To enhance the ionic conductivity and power density of low-temperature SOFCs.
• To understand the role of grain boundaries and interfaces in ion transport.

Main Methods:

• Fabrication of nanocrystalline cerium gadolinium oxide (Ce_0.9Gd_0.1O_2-δ) electrolytes.
• Characterization of ionic conductivity at various temperatures.
• Fabrication and testing of a fuel cell utilizing the nanocrystalline GDC electrolyte.
• Analysis of the electrolyte's microstructure and composition under operating conditions.

Main Results:

• The nanocrystalline GDC electrolyte exhibited an ionic conductivity of 0.37 S·cm^-1 at 550 °C.
• A fuel cell with the nanocrystalline GDC electrolyte achieved a peak power density of 591.8 mW·cm^-2 at 550 °C.
• An amorphous layer enriched with oxygen vacancies at nano-GDC particle surfaces facilitated grain boundary diffusion.

Conclusions:

• Ionic conduction at particle interfaces, driven by grain boundary diffusion, is the dominant mechanism in nanocrystalline GDC electrolytes.
• Oxygen ions are the primary charge carriers in this interfacial conduction.
• The nanocrystalline GDC electrolyte offers a significant improvement over traditional GDC electrolytes for low-temperature SOFC applications.