Studies of the cathode-electrolyte interface of solid oxide fuel cells
Abstract/Contents
- Abstract
- Concerns about global climate change remain a significant driving force for research of energy conversion devices. Solid oxide fuel cells (SOFCs) are one such device. Several recent advances in SOFCs have focused on reducing the ohmic losses of the device, either through thinner electrolyte membranes, or higher ionic conductivity of the electrolyte. As these advances allow for the operation of SOFCs at lower temperatures, the major source of loss within these devices shifts to the interfaces. In particular, the activation losses at the cathode and cathode-electrolyte interface become the dominant bottleneck in the operation of SOFCs at lower temperatures. In this work, three studies on the cathode or cathode-electrolyte interface of SOFCs will be presented. Additionally, electrochemical impedance spectroscopy (EIS) is used as a tool for interpreting the types and amount of loss present in SOFCs under various fabrication and operational conditions. In the first study, thin films of LSCF, a mixed electronic-ionic conducting (MEIC) material, are deposited by pulsed laser deposition (PLD) and used as the cathode material for SOFCs. Research results indicate the presence of an optimal cathode thickness for maximum power performance, which is obtained by minimizing the sum of the electronic and ionic resistances of the cathode material. However, the results indicate the catalytic activity of this material severely limits SOFC performance at lower temperatures. In the second study, the effects of ion irradiation at the cathode-electrolyte interface of SOFCs are studied. In particular, the IV performance is observed as a function of irradiation energy for both xenon and sodium ions at a dose of 1E16 ions per square centimeter. Results indicate that xenon ion irradiation at low energy (70keV and below) produces an increase of more than 100% in the peak power density at 310°C, by reducing the activation losses of the SOFCs, while sodium irradiation produces little effect. Both xenon and sodium ion irradiation result in significantly worse performance at high irradiation energy (150 keV and above). Secondary ion mass spectrometry (SIMS) was used to verify the depth profile of the implanted ions, which compared favorably with simulations performed using a Kinetic Monte Carlo (KMC) model. Additionally, transmission electron microscopy (TEM) was used to visualize the damage created in the electrolyte substrates under various irradiation conditions. The final study looks at the role of electrolyte grain-boundaries at the cathode-electrolyte interface. Results from EIS measurements, quantum simulations, and SIMS analysis indicate that oxide ion incorporation from the cathode into the electrolyte is enhanced at grain boundaries of the electrolyte.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Copyright date | 2010 |
| Publication date | 2009, c2010; 2009 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Crabb, Kevin Matthew |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering |
| Primary advisor | Prinz, F. B |
| Thesis advisor | Prinz, F. B |
| Thesis advisor | Cui, Yi, 1976- |
| Thesis advisor | McIntyre, Paul Cameron |
| Advisor | Cui, Yi, 1976- |
| Advisor | McIntyre, Paul Cameron |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kevin Matthew Crabb. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2010. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Kevin Matthew Crabb
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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