One major drawback, which constrains the lifetime of 8.5 mol% yttria-doped zirconia (8YDZ) as electrolyte material for SOFCs, is the degradation in ionic conductivity under-application relevant conditions. In analogy to pure YDZ electrolyte materials, a degradation in ionic conductivity is observed for YDZin SOFC Ni/YDZ cermet (cermet = ceramic metallic) anodes. However, this degradation is found to be about two orders of magnitude faster compared to the degradation of “pure” YDZ. The reason of this is assumed to be an in-diffusion of Ni ions into the 8YDZ during the sintering (1400°C, 5h) which may strongly affect the mobility of Y and Zr ions in 8YDZ.
A. Lefarth, B. Butz, H. Störmer, A. Utz, D. Gerthsen, Impact of Ni on Accelerated Degradation of 8.5 mol% Y2O3 doped Zirconia, ECS Transactions 35, 1581 (2011)
B. Butz, A. Lefarth, H. Störmer, A. Utz, E. Ivers-Tiffée, D. Gerthsen, Accelerated Degradation of 8.5 mol% Y2O3 doped Zirconia by dissolved Ni, Solid State Ionics 2014, 37 (2012), DOI:10.1016/j.ssi.2012.02.023
J. Szász, D. Klotz, H. Störmer, D. Gerthsen, E. Ivers-Tiffée, Nanostructures Ni/YSZ Anodes: Fabrication and Performance Analysis, ECS Transactions 57, 1469 (2013)