La_0.6Ca_0.4Fe_0.8Ni_0.2O_3−Δ – Sm_0.2Ce_0.8O_1.9 composites as symmetrical bi-electrodes for solid oxide fuel cells through infiltration and in-situ exsolution

Symmetrical solid oxide fuel cells (SOFCs) have more attractive benefits such as a simplified fabrication procedure and enhanced stability and reliability compared to conventional SOFC. In this study, we fabricated a La_0.6Ca_0.4Fe_0.8Ni_0.2O_3−δ (LCFN) – Sm_0.2Ce_0.8O_1.9 (SDC) composite via infiltration and simple mixing methods and evaluated it as both anode and cathode for symmetrical SOFCs (S-SOFC). X-ray diffraction (XRD) and scanning electron microscope (SEM) results demonstrated that Fe-Ni bimetallic nanoparticles were exsolved in-situ from LCFN perovskite and distributed on the surface of LCFN backbone after H₂ reduction at high temperature. The electro-activity towards oxygen reduction reaction (ORR) at the cathode side could be further improved by infiltration of SDC nanoparticles. A combined effect of in-situ ex-solution of Fe-Ni as well as infiltration of SDC nanoparticles synergistically promoted the hydrogen oxidation reaction at the anode and ORR activity at the cathode. Furthermore, the S-SOFC showed good stability in H₂ at 800 °C for 140 h and reliable redox stability undergoing a repeated H₂-air cycles. These recent results indicate that the LCFN-SDC composite electrodes were promising bi-electrode materials for high performance and cost-effective S-SOFCs.