Degradation of the beta-alumina electrolyte in a zebra cell

 

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dc.contributor.advisor Hutchings, Ron en_ZA
dc.contributor.advisor Ball, Anthony en_ZA
dc.contributor.author Van Heerden, D P en_ZA
dc.date.accessioned 2016-03-14T07:01:52Z
dc.date.available 2016-03-14T07:01:52Z
dc.date.issued 1988 en_ZA
dc.identifier.citation Van Heerden, D. 1988. Degradation of the beta-alumina electrolyte in a zebra cell. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/17666
dc.description Bibliography: pages 103-106. en_ZA
dc.description.abstract Beta-alumina solid electrolytes studied were subjected to charge and discharge cycles in a secondary, high energy density Na/beta-alumina/NaAlCl₄/FeCl₂ cell (known as the Zebra cell) at 250⁰ C. These electrolytes were studied by means of optical microscopy, as well as SEM and EDS analyses to est ablish possible failure modes. After cycling little discolouration, or impurity pickup was found to have occurred in the electrolyte. The forms of degradation of the beta-alumina electrolyte identified appeared to be a result of inherent flaws in the beta-alumina electrolyte tube, problems due to protracted storage of the tubes, or an apparent interfacial film on the cathode/electrolyte interface. A lead wetting agent was used in the cells to enhance the wetting of the beta-alumina electrolyte by the liquid Na. A study of the coating after cycling of the cell showed that the coating was adherent irrespective of the number of cycles completed. The coating did not appear to influence cracking of the electrolyte during cycling. Cracking of the beta-alumina electrolyte was found to have initiated from the Na/electrolyte interface. No evidence of crack initiation nor internal damage was found on the cathode/electrolyte interface. The cracks through the beta-alumina electrolyte wall were found to have sealed by the formation of a plug consisting largely of Na and Cl. On the basis of EDS analyses of the fracture surface of the sealed crack possible sealing mechanisms are proposed. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Electrolytes en_ZA
dc.subject.other Electrolyte solutions en_ZA
dc.title Degradation of the beta-alumina electrolyte in a zebra cell en_ZA
dc.type Master Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering and the Built Environment
dc.publisher.department Centre for Materials Engineering en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Van Heerden, D. P. (1988). <i>Degradation of the beta-alumina electrolyte in a zebra cell</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering. Retrieved from http://hdl.handle.net/11427/17666 en_ZA
dc.identifier.chicagocitation Van Heerden, D P. <i>"Degradation of the beta-alumina electrolyte in a zebra cell."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 1988. http://hdl.handle.net/11427/17666 en_ZA
dc.identifier.vancouvercitation Van Heerden DP. Degradation of the beta-alumina electrolyte in a zebra cell. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Materials Engineering, 1988 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/17666 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Van Heerden, D P AB - Beta-alumina solid electrolytes studied were subjected to charge and discharge cycles in a secondary, high energy density Na/beta-alumina/NaAlCl₄/FeCl₂ cell (known as the Zebra cell) at 250⁰ C. These electrolytes were studied by means of optical microscopy, as well as SEM and EDS analyses to est ablish possible failure modes. After cycling little discolouration, or impurity pickup was found to have occurred in the electrolyte. The forms of degradation of the beta-alumina electrolyte identified appeared to be a result of inherent flaws in the beta-alumina electrolyte tube, problems due to protracted storage of the tubes, or an apparent interfacial film on the cathode/electrolyte interface. A lead wetting agent was used in the cells to enhance the wetting of the beta-alumina electrolyte by the liquid Na. A study of the coating after cycling of the cell showed that the coating was adherent irrespective of the number of cycles completed. The coating did not appear to influence cracking of the electrolyte during cycling. Cracking of the beta-alumina electrolyte was found to have initiated from the Na/electrolyte interface. No evidence of crack initiation nor internal damage was found on the cathode/electrolyte interface. The cracks through the beta-alumina electrolyte wall were found to have sealed by the formation of a plug consisting largely of Na and Cl. On the basis of EDS analyses of the fracture surface of the sealed crack possible sealing mechanisms are proposed. DA - 1988 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1988 T1 - Degradation of the beta-alumina electrolyte in a zebra cell TI - Degradation of the beta-alumina electrolyte in a zebra cell UR - http://hdl.handle.net/11427/17666 ER - en_ZA


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