Solid oxide cells with nickel/yttrium-stabilized zirconia (Ni/YSZ) cermet electrodes exhibit Ni migration which can cause severe cell performance degradation. The experimentally reported migration behavior of Ni is complicated, and the mechanisms remain under debate. This work discusses the possible mechanism of Ni migration related to the oxidation of Ni at the Ni-electrolyte interfaces under polarization via combined experimental study and theoretical analysis. In the experiments, NiO is found at the Ni-YSZ interfaces in the active layer in both tested fuel cells and electrolyzer cells, despite that the nominal oxygen partial pressure at the hydrogen electrode is well below the thermodynamic threshold for Ni oxidation. Due to the volume expansion during Ni oxidation and the outward diffusion nature of NiO growth, Ni oxidation and reduction of NiO back to Ni can cause Ni relocation. Thermodynamic analysis shows that the oxygen partial pressure near the Ni-electrolyte interface can be significantly higher than the hydrogen electrode under polarization, which can cause Ni oxidation and concentration increase of the gaseous Ni(OH)₂, and the latter accelerates the transport of Ni. As such, a new hypothesis for Ni migration in solid oxide cells is proposed in which the interfacial oxidation of Ni plays an essential role.

具有镍/钇稳定氧化锆 (Ni/YSZ) 金属陶瓷电极的固体氧化物电池表现出 Ni 迁移，这会导致电池性能严重下降。实验报告的 Ni 迁移行为很复杂，其机制仍存在争议。这项工作通过实验研究和理论分析相结合，讨论了极化条件下与 Ni 电解质界面处 Ni 氧化相关的 Ni 迁移的可能机制。在实验中，尽管氢电极的标称氧分压远低于 Ni 氧化的热力学阈值，但在测试的燃料电池和电解槽电池的活性层的 Ni-YSZ 界面处都发现了 NiO。由于 Ni 氧化过程中的体积膨胀和 NiO 生长的向外扩散性质，Ni 氧化和 NiO 还原回 Ni 会导致 Ni 迁移。热力学分析表明，在极化作用下，Ni-电解质界面附近的氧分压明显高于氢电极，这会导致 Ni 氧化和气态 Ni(OH)₂，后者加速了Ni的传输。因此，提出了固体氧化物电池中 Ni 迁移的新假设，其中 Ni 的界面氧化起着至关重要的作用。