© 2012 EPFL
RedOx Stability of Anode Supported Solid Oxide Fuel Cells. Thèse EPFL, no 4893 (2011). Dir.: Jan Van herle, Aïcha Hessler-Wyser.
"for his remarkable contribution to understanding the mechanisms of metal reoxidation in a metal-ceramic composite and their effect on the dimensional stability and reliability of a fuel cell device during operation, including the development and validation of a new robust microstructure for the device"
Abstract: Global energy demand is exponentially increasing and fossil resources are limited. Fuel cells can play a major role in this general context as it converts chemical energy to electricity (and vice versa) with unrivalled high efficiency (even for small system <1 kW). Solid oxide fuel cells (SOFC) stand out with the highest potential for electrical and overall efficiency (using co-generation), wide fuel flexibility (from both fossils and renewables), and absence of corrosive liquids and noble metals. One of the major weakness of nickel-based SOFC anodes is their low ability to withstand re-oxidation at working temperature, especially for the anode-supported cell design. The volume expansion coming along with nickel (Ni) oxidation induces stresses in the layers and cracks especially for the thin supported electrolyte.
This work first characterizes the Ni re-oxidation process using different microscopy techniques from the nanometer scale (by in situ transmission electron microscopy) and the micrometer scale (by scanning electron microscopy) to macrometer scale. Secondly, the anode composition and microstructure is optimized through design of experiment approach. Finally, three different anode support microstructures are tested at laboratory scale and one is successfully implemented within a pre-commercial design.