This thesis presents an exploration of Solid Oxide Membrane (SOM) electrolysis as a solution to the imminent challenge of transitioning from fossil fuel dependence towards sustainable, low-carbon energy technologies. Two key applications are explored: the production of solar-grade silicon for photovoltaic cells and the recycling of iron as an electrofuel.
Solid Oxide Membrane (SOM) based electrolysis process is a promising technology that has been demonstrated to successfully produce many energy-intensive metals directly from their oxides in an efficient, economical and environmentally sound way. First, the production of solar-grade silicon from silica via a single-step SOM electrolysis process (Si-SOM) is demonstrated. During the Si-SOM electrolysis process, an yttria-stabilized zirconia (YSZ) tube was employed to separate pre-engineered molten flux with dissolved silica from the anode assembly. When the applied DC potential between the cathode and the anode exceeds the dissociation potential of silica, silicon is reduced at the cathode, while oxygen ions migrate through the YSZ membrane and are oxidized at the anode. The Si-SOM electrolytic cell design and process parameters are optimized to enable high-purity silicon deposition on the cathode and ensure stable and efficient Si-SOM electrolysis. Electrochemical characterization and modeling of the Si-SOM electrolysis are also presented with detailed microstructural analysis of the silicon deposits.
In parallel, this thesis demonstrates an innovative method of reducing the iron oxide to iron via a molten salt-free SOM electrolysis (Fe-SOM). Iron oxide and liquid silver as the reducing medium are contained in a one-end closed YSZ membrane. The soluble oxygen is pumped out of liquid silver with an applied potential between the cathode and the anode to create a reducing condition that is sufficient to reduce the iron oxide. The Fe-SOM electrolytic cell design and process parameters are optimized to enable high-efficiency and stable electrolysis of iron oxide. Electrochemical characterization of the Fe-SOM electrolysis is also presented with detailed microstructural analysis of the iron deposits.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/46663 |
| Date | 30 August 2023 |
| Creators | Yan, Haoxuan |
| Contributors | Pal, Uday |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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