Microstructural Change of Ni–YSZ Anode under Thermal Cycles with Redox Treatments

Abstract

Nickel–yttria-stabilized zirconia (Ni–YSZ) is widely used as an anode material for solid oxide fuel cells (SOFCs). However, it is concerned that the performance of Ni–YSZ anode is deteriorated by redox treatments accompanied with the microstructural change. In this study, we investigated the correlation between the performance deterioration and the microstructural change of Ni–YSZ anode subjected to thermal cycles with redox treatments (thermal–redox cycles: repetition of oxidation in cooling and reduction in heating processes). The microstructural change of anode was quantified by focused ion beam–scanning electron microscopy (FIB–SEM). The decrease in the active triple phase boundary (TPB) length caused by sintering of Ni particles was correlated with the performance deterioration. We also found that the reduction onset temperature at 500 ºC in the heat-up process promoted the agglomeration of Ni particles as compared with that at 900 ºC.