Self-Compressive Stress Promoting Densification of Proton-Conducting Electrolyte Membranes.

Area of Science:

• Materials Science
• Electrochemistry
• Ceramic Engineering

Background:

• Dense asymmetric ceramic membranes are crucial for solid oxide cells (SOCs) and gas separation.
• Proton-conducting SOCs offer efficient power and hydrogen generation at lower temperatures.
• High-temperature sintering of electrolytes like BaCe_0.7Zr_0.1Y_0.2O_3-δ (BCZY712) leads to detrimental elemental volatilization and segregation, reducing performance.

Purpose of the Study:

• To introduce a self-compressive stress strategy for improved densification of BCZY712 proton-conducting electrolyte layers.
• To investigate the effect of controlled compressive stress on electrolyte densification and properties.
• To enhance the performance of proton-conducting solid oxide cells by optimizing electrolyte fabrication.

Main Methods:

• Implementing a self-compressive stress strategy by regulating pore former content and anode substrate pre-sintering temperature.
• Applying compressive stress to the BCZY712 electrolyte layer during co-sintering.
• Characterizing the densification, microstructure, and ionic conductivity of the electrolyte.

Main Results:

• Achieved a relative density of ~99% for the BCZY712 electrolyte layer at a reduced sintering temperature (~150 °C lower).
• Effectively suppressed barium evaporation, Y₂O₃ impurity segregation, and Ni migration.
• Observed a 151% increase in electrolyte conductivity and an 89% improvement in peak power density of the SOC.

Conclusions:

• The self-compressive stress strategy is a viable method for fabricating high-density proton-conducting ceramic electrolytes.
• Reduced co-sintering temperatures significantly mitigate performance-limiting defects.
• This approach offers a pathway to enhanced solid oxide cell performance for energy applications.