Relation between shape of Ni-particles and Ni migration in Ni-YSZ electrodes – a hypothesis

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Abstract

This is an attempt to explain a phenomenon of total depletion of Ni next to the electrolyte in Ni-YSZ cermet electrodes in solid oxide electrolysis cells during electrolysis at high current density/overpotential. Intuitively, we would think that Ni would always migrate down the steam partial pressure (pH2O) gradient as previously observed [1], but in the present cases Ni seems to migrate up the pH2O gradient. However, it is also observed that there is a preceding phase in this Ni-YSZ electrode degradation, namely that the Ni-particles closest to the YSZ electrolyte loose contact to each other. This means that the active three phase boundary (TPB) moves away from the electrolyte and causes a significant increase in the ohmic resistance as is also observed in electrochemical impedance spectra.
Original languageEnglish
Title of host publicationProceedings of the 12th European SOFC & SOE Forum
Number of pages8
PublisherEuropean Fuel Cell Forum
Publication date2016
Article numberA0902
ISBN (Print)978-3-905592-21-4
Publication statusPublished - 2016
Event12th European SOFC & SOE Forum - Lucerne, Switzerland
Duration: 5 Jul 20168 Jul 2016
Conference number: 12
http://www.efcf.com/index.php?id=1954

Conference

Conference12th European SOFC & SOE Forum
Number12
CountrySwitzerland
CityLucerne
Period05/07/201608/07/2016
Internet address

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