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Title: Investigating the effects of thermally driven degradation in solid oxide fuel cells
Author: Heenan, Thomas Michael McDougal
ISNI:       0000 0004 7660 5110
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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One of the most promising devices for low-carbon energy conversion is the solid oxide fuel cell (SOFC). Theoretically, SOFCs show great potential; operating at temperatures between 600-1000 °C the SOFC allows fast reaction kinetics and fuel versatility without the need for expensive platinum catalysts. However in practice, SOFCs can suffer from considerable losses in electrochemical performance due to a multitude of complex degradation mechanisms. This thesis aims to expand our understanding of such mechanisms. Techniques for the three-phase segmentation of SOFC anode materials using nano X-ray computed tomography (CT) and 4D X-ray CT are demonstrated using lab-based instruments, previously only possible using specialist synchrotron facilities. Subsequently, a series of degradation studies are conducted across multiple length-scales using a combination of absorption and diffraction X-ray characterisation methods. Firstly a macroscopic X-ray CT investigation is carried out at cell-level inspecting the effect of start-up time on the delamination of the anode from the electrolyte. Secondly, a microscopic X-ray CT study is conducted on the particle-particle interaction within the anode during operational thermal cycling. Finally, a crystallographic investigation is conducted using synchrotron X-ray powder diffraction to understand the thermo-mechanical properties of anode materials. The experiments reported here improve our understanding of the intrinsic link between the mechanical and electrochemical performance of SOFCs and the influence of microstructure. Understanding is gained from the importance of the materials chosen during manufacturing to the effects of the thermal profiles during operation. These findings are expected to influence the future of SOFC technology from fundamental research to commercial application.
Supervisor: Shearing, P. ; Brett, D. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available