Tailored Sr-Co-free perovskite oxide as an air electrode for high-performance reversible solid oxide cells

Sr-Co containing perovskite oxides are prospective air electrode candidates for reversible solid oxide cells (RSOCs). However, their efficiencies are limited by Sr segregation and the high thermal expansion coefficient (TEC) of Co-based perovskites. Herein, La0.6Ca0.4Fe08Ni0.2O3−δ (LCaFN) is tailored as an Sr-Co-free perovskite air electrode for highperformance RSOCs. Compared with La0.6Sr0.4Fe0.8Ni0.2O3−δ (LSFN) and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCoF), LCaFN has a high electrical conductivity (297 S cm−1), TEC compatibility (11.2 × 10−6 K−1) and improved chemical stability. Moreover, LCaFN has high oxygen reduction reaction (ORR) activity with a low polarization resistance (0.06 Ω cm2) at 800°C. A single-cell Ni-YSZ/YSZ/gadolinium-doped ceria (GDC)/LCaFN-GDC operated at 800°C yields a maximum power density of 1.08 W cm−2 using H2 as fuel. In the solid oxide electrolysis cell (SOEC) mode, the cell can achieve a current density of approximately 1.2 A cm−2 at 1.3 V with 70% humidity at 800°C. The cell exhibits good reversibility and remains stable in continuous SOEC and solid oxide fuel cell (SOFC) modes. These findings indicate the potential application of La0.6Ca0.4Fe0.8-Ni0.2O3−δ as an air electrode material for RSOCs.