Anion doping induced lattice contraction retarding Sr segregation for highly active and stable tubular reversible solid oxide cell air electrode

Tubular reversible solid oxide cells (T-RSOCs) facilitate efficient chemical-electrical energy interconversion, advancing renewable energy utilization. However, commercial applications require T-RSOCs to meet long-term high-temperature operating conditions, which imposes higher demands on the stability of T-RSOC components, particularly the air-electrode materials. Herein, the use of anion fluoride doping in SrCo_0.9Ta_0.1O_3-δ (SCT) forming SrCo_0.9Ta_0.1O_3-δF_x (SCTFx) regulates the perovskite lattice size to suppress Sr migration and segregation within the material, thereby enhancing the anti-poisoning capability at elevated temperatures. With SCTFx air electrode, the peak power density of the T-SOC reaches 1141.5 mW cm⁻² at 800 °C, higher than the T-SOC with SCT air electrode (865.2 mW cm⁻²), which is attributed to the shorter oxygen diffusion distance resulting from the lattice contraction. Additionally, the lattice contraction increases the Sr migration energy barrier from 2.13 eV for SCT to 2.67 eV for SCTF10, bringing an excellent stability and anti Cr-poisoning for SCTF electrode. As a result, the T-SOC with SCTF10 air electrode exhibits no significant decline under the stability test and the reversible cycling operation between fuel cell mode and electrolysis cell mode.