Bismuth is a common additive of commercial silver pastes for enhancing metallization effect; silver paste is also commonly used in high-temperature electrochemical cells as a current collector or contact layer. We here report that the minor amount of bismuth in commercial silver pastes can transport to the interface of electrode/Gd-doped CeO2 (GDC) electrolyte and seriously corrode grain-boundaries (GBs) of the GDC electrolyte, a commonly used intermediate-temperature electrolyte, causing significant ionic conductivity degradation. A comprehensive electron microscopic analysis reveals that the Bi-corrosion takes place along GBs of GDC electrolyte acting as “washing flux” agent, causing grain separation and thus blocking ionic conduction. It is also found that electrical field enhances the “Bi-washing” effect, leading to a faster degradation in full-cell than in half-cell. Overall, the use of commercial silver paste as a current collector for CeO2-based electrolytes in long-term testing should be cautioned.
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Published in Journal of The Electrochemical Society, Volume 165, Issue 13, 2018, pages F1110-F1114.
© The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.
Yang, T., & Huang, K. (2018). A Bismuth Attack at Grain-Boundaries of Ceria-Based Electrolytes. Journal Of The Electrochemical Society, 165(13), F1110-F1114. doi: 10.1149/2.1091813jes