A perovskite La0.2Sr0.8Co0.8Fe0.2O3−δ catalyst exhibited remarkably high activities for the ORR and OER as a novel bifunctional oxygen electrode for reversible SOCs.

The solid oxide electrolysis cell (SOEC) and its developement are in an increasing focus, because of its high efficiency and eco-friendliness in storing energy by converting electrical energy into hydrogen. Recently, research has been conducted to decrease the operation temperature of SOECs below 750°C to overcome high system costs and rapid degradation rate at high operation temperatures. Although La 0.6 Sr 0.4 Co 0.2-Fe 0.8 O 3-d (LSCF) is a promising oxygen electrode for SOEC, when the operating temperature is reduced, the reaction kinetics of the LSCF oxygen electrode is significantly decreased due to high activation energy of the oxygen ion transport. To address this issue, we developed a composite oxygen electrode of LSCF combined with Gd and Nd double doped ceria (GNDC). Due to excellent oxygen ion transport nature of GNDC, the SOEC with the LSCF-GNDC oxygen electrode yielded impressive current density of 1,174 mA cm-2 at 1.3 V at 750°C along with excellent stability. These results demonstrated that the novel LSCF-GNDC composite is promising as an efficient and durable oxygen electrode for SOEC applications.

Solid oxide cells (SOCs) have been reported as promising energy production and storage devices due to their high efficiency and low pollutant emissions. A key barrier to achieve high performance of SOCs is high electrode polarization resistance which attributes to the sluggish kinetics of oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) at reduced temperatures. One of the potential oxygen electrodes is a perovskite La0.6Sr0.4Co0.2Fe0.8O3- δ(LSCF6428) with mixed ionic and electronic conduction (MIEC) because of its considerable conductivities and good chemical compatibility with conventional electrolyte materials such as ceria-based oxides. However, upon long-term operation under fuel cell conditions, the LSCF6428 electrode is usually subjected to severe degradation of ORR kinetics owing to chemical instability. It has been well known that the tailoring the chemical composition of the perovskite material strongly modulates their electrochemical activities and oxygen ion transport properties. In this study, we synthesized the La0.2Sr0.8Co0.8Fe0.2O3- δ (LSCF2882) and systematically investigated its characteristics on intrinsic properties. In addition, we evaluated oxygen transport kinetics and electrochemical performance of LSCF2882 as an oxygen electrode for reversible SOC applications.