THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING

GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

MASTER OF SCIENCE

on Thursday, April 25, 2019

10:00 AM
in MoSE 1201A

will be held the

MASTER’S THESIS DEFENSE

for

Yuchen Liu

“Stability of Double Perovskite Cathodes Under High Humidity for Solid Oxide Fuel Cells”

Committee Members:

Prof. Meilin Liu, Advisor, MSE

Prof. Preet Singh, MSE

Prof. Faisal Alamgir, MSE

Abstract:

Solid Oxide Fuel Cells (SOFCs) can directly convert a wide variety of fuels to electricity efficiently.  They can also be run in reverse as Solid Oxide Electrolysis Cells (SOECs) to produce hydrogen (and carbon-containing fuels) from electrolysis of water (and carbon dioxide). However, the kinetics of oxygen reduction reaction (ORR) on the cathode is often hindered by various contaminants, which may react with the cathode to form insulating phases and degrade fuel cell performance. The stability and performance of the cathode in moisture is critical to the cell performance as SOFCs and SOECs. Several state-of-the-art cathode materials are investigated in a high moisture environment to uncover their performance and degradation mechanism. First, powders of electrode materials were analyzed for any degradation before and after long-term moisture exposure using XRD to probe the bulk and Raman Spectroscopy to probe the surface. SEM was also used to characterize any morphological changes during the exposure. Second, electrochemical impedance spectroscopy (EIS) was used to monitor the long-term performance of symmetric cells under various conditions. Finally, current-voltage relationships of symmetric cells were acquired under typical operating conditions for SOFCs and SOECs to determine the polarization resistance, stability and durability of the cathode materials.