PhD Prospectus Defense: John-In Lee

MSE PhD Prospectus Defense: John-In Lee

TITLE: Degradation Behavior Of Non-Infiltrated And GDC-Infiltrated Reversible Solid Oxide Cells Under Long-Term Operation

ADVISOR: Uday Pal MSE

COMMITTEE: Soumendra Basu MSE, Srikanth Gopalan MSE, Jörg Werner MSE

ABSTRACT: Reversible solid oxide cells (RSOCs) are regarded as promising energy conversion system that operate efficiently in both modes, fuel cell (FC) and electrolysis cell (EC). In spite of their potentials, RSOCs are not widely used because of durability issues related to many degradation factors. Among these, barrier layer detachment and microstructural degradation at the fuel electrode are known to be major degradation factors. In this research, cells with stable and robust barrier layers were manufactured, allowing fuel electrode-focused research to be performed. This research focused on understanding the degradation factors followed by improving the performance and durability of the fuel electrode. The cells were operated under various conditions, including different operating modes such as EC only and reversible cell (RSOC) operation, which alternates between FC and EC, to investigate fuel electrode degradation factors. Additionally, gadolinium-doped ceria (GDC) was infiltrated into the fuel electrode to enhance the durability and performance of RSOCs. Non-infiltrated and GDC-infiltrated cells were operated under harsh condition, galvanostatic electrolysis for 500 hours, and under less harsh condition, potentiostatic RSOC operation for 1000 hours. The electrochemical properties of the cells were measured using I-V curves, EIS and DRT analyses during the operations. Under both operating conditions, the barrier layer of the cells remained intact, and fuel electrode degradation was confirmed. Additionally, the effect of GDC infiltration was demonstrated to improve the performance and durability of cells. GDC increased the performance by increasing the triple phase boundary (TPB) length and mitigating the diffusion related degradation at the fuel electrode.