Phase stability of LiAlO{sub 2} in molten carbonate
- Toshiba Corp., Kawasaki (Japan). Materials and Devices Research Labs.
In current molten carbonate fuel cells (MCFCs), submicron {gamma}-LiAlO{sub 2} powder is used as the electrolyte-retaining material because of its stability at high temperatures. However, it is recognized that {gamma}-LiAlO{sub 2} transforms to mainly {alpha}-LiAlO{sub 2} during MCFC operation. This suggests that {gamma}-LiAlO{sub 2} behavior in molten carbonate is different from that in air. To confirm the stable allotropic phase under actual MCFC conditions, the authors investigated the phase transformation of LiAlO{sub 2} in the presence of molten carbonate. It was found that essentially the {alpha}-phase is stable in a low-temperature and high-p{sub CO{sub 2}} environment, whereas the {gamma}-phase is stable in a high-temperature and low-p{sub CO{sub 2}} environment. In addition, there exists relative particle size dependence of the allotropic transformation when {alpha}- and {gamma}-LiAlO{sub 2} powders coexist. Further, the authors confirmed that the phase composition and structure of a matrix which consists of the {alpha}-LiAlO{sub 2} powder is stable up to 7,550 h at 700 C when the powder particle diameter is 0.3 {micro}m. These results suggest that {alpha}-LiAlO{sub 2} powder with 0.3 {micro}m diam is preferred over conventional {gamma}-LiAlO{sub 2} powder as an electrolyte-retaining material in MCFCs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 603731
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 12 Vol. 144; ISSN 0013-4651; ISSN JESOAN
- Country of Publication:
- United States
- Language:
- English
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