La_0.6Sr_0.2Co_0.2Fe_0.8O_3-δ (LSCF) is the most intensively investigated high performance cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs), but strontium segregation and migration at the electrode/electrolyte interface is a critical issue limiting the electrocatalytic activity and stability of LSCF based cathodes. Herein, we report a Nb and Pd co-doped LSCF (La_0.57Sr_0.38Co_0.19Fe_0.665Nb_0.095Pd_0.05O_3-δ, LSCFNPd) perovskite as stable and active cathode on a barrier-layer-free anode-supported yttria-stabilized zirconia (YSZ) electrolyte cell using direct assembly method without pre-sintering at high temperatures. The cell exhibits a peak power density of 1.3 W cm⁻² at 750 °C and excellent stability with no degradation during polarization at 500 mA cm⁻² and 750 °C for 175 h. Microscopic and spectroscopic analysis show that the electrochemical polarization promotes the formation of electrode/electrolyte interface in operando and exsolution of Pd/PdO nanoparticles. The Nb doping in the B-site of LSCF significantly reduces the Sr surface segregation, enhancing the stability of the cathode, while the exsoluted Pd/PdO nanoparticles increases the electrocatalytic activity for the oxygen reduction reaction. The present study opens up a new route for the development of cobaltite-based perovskite cathodes with high activity and stability for barrier-layer-free YSZ electrolyte based IT-SOFCs.

La _0.6 Sr _0.2 Co _0.2 Fe _0.8 O3 _-δ（LSCF）是用于中温固体氧化物燃料电池（IT-SOFC）的研究最深入的高性能阴极，但是锶在电极/电解质界面的偏析和迁移至关重要问题限制了基于LSCF的阴极的电催化活性和稳定性。在此，我们报告了Nb和Pd共掺杂的LSCF（La _0.57 Sr _0.38 Co _0.19 Fe _0.665 Nb _0.095 Pd _0.05 O3 _-δ（LSCFNPd）作为钙钛矿，是采用直接组装法在无阻挡层的阳极支撑的氧化钇稳定的氧化锆（YSZ）电解质电池上作为稳定的活性阴极，无需在高温下进行预烧结。该电池在750°C时表现出1.3 W cm ^-2的峰值功率密度，并且具有出色的稳定性，并且在极化过程中在500 mA cm ^-2和750°C下持续175 h时没有降解。显微和光谱分析表明，电化学极化促进了操作中电极/电解质界面的形成和Pd / PdO纳米粒子的析出。LSCF B位的Nb掺杂显着降低了Sr表面偏析，增强了阴极的稳定性，而溶出的Pd / PdO纳米颗粒则增加了氧还原反应的电催化活性。本研究为开发基于钴的钙钛矿型阴极提供了一条新途径，该阴极对无阻挡层的YSZ电解质基IT-SOFC具有高活性和稳定性。