The characteristics of the various migration types are apparently of different nature varying from: (i) Ni-particle migration on top of the YSZ electrolyte in a model electrode to (ii) long distance Ni migration out of porous Ni-YSZ composite cermet electrode in solid oxide fuel cells (SOFCs), and (iii) migration of Ni towards the YSZ electrolyte at 950 C, but away from the electrolyte at temperatures below 875 C under otherwise similar conditions in Ni-YSZ cermet electrodes in SOECs.
Apart from temperature, degradation of Ni-YSZ electrodes in SOCs is related to overpotential and partial pressure of steam (pH2O), hydrogen (pH2), carbon dioxide (pCO2), carbon monoxide (pCO) and oxygen (pO2) through the influence of these parameters on the mobility of Ni. Actually, the local partial pressure values are most important. Furthermore, impurities from cell materials and reactants may increase mobility of Ni and in general highly affect the long-term durability of SOECs negatively.
Possible Ni migration mechanisms and methods of mitigating the degradation associated with Ni migration are discussed. It is concluded that a lot of further work is necessary in order to describe this Ni migration properly, and the type of work is listed.
|Number of pages||9|
|Publication status||Published - 2020|
|Event||14th European SOFC & SOE Forum 2020 - Lucerne, Switzerland|
Duration: 22 Oct 2020 → 23 Oct 2020
Conference number: 14
|Conference||14th European SOFC & SOE Forum 2020|
|Period||22/10/2020 → 23/10/2020|