莫来石结构氧化物具有优异的氧还原反应(ORR)活性，得益于其独特的晶体结构而表现出较低的热膨胀系数(TEC)，且由于不含碱土元素，可避免使用阻挡层并简化制备工艺。因此，它们作为新型固体氧化物燃料电池(SOFC)阴极材料具有广阔的应用前景。本工作通过固-液复合路线一步法合成了莫来石-尖晶石结构的SmMn₂O₅-NiMn₂O₄(SMO-NMO)复合阴极，其原位自组装特性使其在无需阻挡层的情况下即可与电解质实现良好的界面匹配。表征结果表明，当SMO:NMO=5:5 (SN55)时，复合阴极通过两相之间的协同作用，克服了单相材料的性能瓶颈-即纯SMO导电性低(800 °C时仅为0.035 S cm^-1)以及纯NMO氧还原反应(ORR)活性不足的问题。在800 °C下，全电池的峰值功率密度达到1069.82 mW cm^-2，分别为纯SMO(329.92 mW cm^-2)和纯NMO(890.20 mW cm^-2)的3.24倍和1.20倍。以SN55为阴极的全电池在750 °C、540 mA cm^-2条件下恒流放电150 h后，电压衰减约为1.6%，平均衰减率为5.62%/kh，且阴极-电解质界面未出现任何缺陷与元素偏析。本研究为设计无阻挡层固体氧化物燃料电池（SOFC）阴极材料提供了一条新的思路。

Mullite-structured oxides exhibit excellent oxygen reduction reaction (ORR)activity, possess a low thermal expansion coefficient (TEC)due to their unique crystal structure, and can eliminate the need for a barrier layer and simplify the preparation process as they contain no alkaline earth elements. Thus, they hold great promise as novel cathode materials for solid oxide fuel cells (SOFCs). In this work, a mullite-spinel-structured SmMn₂O₅-NiMn₂O₄ (SMO-NMO)composite cathode was one-step synthesized via a solid-liquid composite route, and its in-situ self-assembly enabled good compatibility with the electrolyte without any barrier layer. Characterization results showed that the SMO:NMO=5:5 (SN55)composite cathode overcame the bottlenecks of single-phase materials-namely, the low conductivity of pure SMO (only 0.035 S cm^-1 at 800 °C)and the insufficient oxygen reduction reaction (ORR)activity of pure NMO-through a synergistic effect between the two phases. At 800 °C, the single cell delivered a peak power density of 1069.82 mW cm^-2, which was 3.24-fold and 1.20-fold higher than that of pure SMO (329.92 mW cm^-2)and NMO (890.20 mW cm^-2), respectively. Under galvanostatic operation at 750 °C (current density corresponding to 540 mA cm^-2), the SN55-based cell runs for ~150 h with only 1.6% voltage loss, corresponding to a degradation rate of 5.62%/kh, and no defects appeared at the cathode-electrolyte interface. This study provided a new route for designing barrier-layer-free cathodes for solid oxide fuel cells (SOFCs).