Probing the long-term thermal stability mechanism of multi-rare-earth oxide-doped zirconia for solid oxide fuel cell electrolyte

The insufficient long-term thermal stability of 8 mol% yttria-stabilized zirconia (8YSZ) is caused by the formation and growth of the short-range ordered structure phase (t" phase). This has limited the feasibility of utilizing this material as a solid electrolyte in solid oxide fuel cells (SOFCs). In this work, the long-term thermal stability of doped zirconia is improved by a multi-rare-earth oxide doping strategy. This strategy leads to lattice distortion and high dislocation density, causing an increase in migration energy (Em), and the association energy (Eass) is lowered. Consequently, the generation of the t" phase is limited, and ionic conductivity does not significantly decrease during annealing. This work offers a new strategy for controlling the lattice distortion in electrolyte materials by regulating the radius and the content of dopants to realize a synergistic improvement in long-term thermal stability and ionic conductivity.