Impact of gadolinium doped ceria infiltrant concentration on fuel electrode microstructure of solid oxide electrolysis cells
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Abstract
In the modern renewable energy landscape, new energy storage and generation systems are necessary to keep up with increasing demand and to allow clean energy to compete with traditional non-renewable energy systems. Solid oxide cells (SOCS) offer a potential low carbon solution to energy generation and storage, with high potential efficiencies and power densities. One challenge of SOCs is degradation of the microstructure during operation, especially the fuel electrode. Liquid infiltration of nanocatalysts, such as gadolinium doped ceria (GDC), into the fuel side electrode is a cost effective, post-fabrication strategy to mitigate performance degradation. This research focuses on understanding how varying the concentration and number of cycles of nanocatalyst infiltration can impact the microstructural degradation of the SOC fuel electrode from operational thermal and humidity effects. Four infiltrant concentrations were examined in this study: uninfiltrated (baseline), 1M GDC with 1 cycle of infiltration (1M-1C), 1M GDC with 3 cycles of infiltration (1M-3C), and 5M GDC with 1 cycle of infiltration (5M-1C). Half cells at each infiltrant concentration were subjected to 3 test conditions: untested, electrochemical t = 0, and 500h under simulated open circuit voltage (OCV) conditions of 800°C under a 50% H2 – 50% H2O atmosphere. Cells infiltrated with the 1M-3C GDC concentration presented the greatest improvement in retaining percolated Ni in the fuel electrode. The 1M-3C cells also presented relatively no Ni particle coarsening in the active layer of the electrode, whereas the 5M-1C cells exhibited the least coarsening in the supporting layer. It was observed that the supporting layer microstructure benefitted the most from GDC infiltration. The GDC morphology within the 1M-3C and 5M-1C fracture surfaces is discussed and related to coarsening of the Ni in the microstructure. The results suggest that the majority of percolated Ni coarsening and loss occurs during the initial ramp up to the start of electrochemical testing. Lastly, when comparing to chemical degradation in the half cells to electrochemical degradation in full solid oxide electrolysis cells (SOECS), GDC infiltration significantly mitigated chemical degradation, making the contribution of electrochemical degradation to the overall degradation of the microstructure more significant.
Description
2025