Improving the fracture toughness of stabilized zirconia-based solid oxide cells fuel electrode supports: Effects of type and concentration of stabilizer(s)

Further development and upscaling of the Solid Oxide fuel and electrolysis Cell (SOCs) technologies would significantly benefit from improvement of their mechanical robustness. In this work, microstructure, crystalline phase composition, fracture toughness and susceptibility to low- and high-temperature degradation of six different Ni(O)‒Zirconia fuel electrode supports, manufactured from six different stabilized zirconia compounds, are investigated. In the oxidized state, tetragonal zirconia-based supports have higher fracture toughness than cubic zirconia-based substrate, due to the transformation toughening effect and a finer grained microstructure. The NiO‒1.5CeO₂ 4.5YO_1.5-SZ support exhibits the highest fracture toughness, showing a 30 and 10 % improvement compared to the state-of-the-art NiO‒5.8YO_1.5-SZ support at room temperature and 800 °C, respectively. In the reduced state on the other hand, the tetragonal and cubic zirconia-based substrates have comparable fracture toughness. The Ceria-Yttria co-doped materials possess superior resistance to hydrothermal degradation due to the stabilizing effect of Ce³⁺ formed during reduction.