Perovskite SrCo0.5Fe0.25Cu0.2Nb0.05O3-δ cathode for intermediate-temperature solid oxide fuel cells: Improved working stability and CO2 tolerance

Abstract

Commercial solid oxide fuel cells (SOFCs) primarily operate in the intermediate temperature range (600 °C–800 °C); hence, developing cathode materials with good stability and excellent catalytic activity in this temperature range is necessary. Herein, we are reporting the performance of SrCo_0.5Fe_0.5O_3−δ (SCF) and SrCo_0.5Fe_0.25Cu_0.2Nb_0.05O_3−δ (SCFCN) perovskite oxide as cathode materials for solid oxide fuel cells (SOFCs). The SCFCN sample maintains a cubic structure under a CO₂ atmosphere. The polarization resistance of the SCFCN cathode on La_0.9Sr_0.1Ga_0.83Mg_0.17O_3−δ (LSGM) reaches 0.067 Ωcm² at 700 °C. The charge transfer and oxygen reduction reactions of the SCFCN cathode on the LSGM electrolyte are the main rate-limiting steps at 600 °C–700 °C. The SCFCN cathode maintains good electrochemical stability during a 200-h test with a configuration of SCFCN/LSGM/SCFCN symmetrical cell. Compared with SCF, the doping of Cu and Nb effectively reduces the Rp attenuation of SCFCN from 0.00012 to 0.00005 Ωcm²/h. The output power density of the fuel cell with SCFCN as the cathode on LSGM reaches 1124 mWcm⁻² at 800 °C. This indicates that SCFCN can be a potential material for fabricating cathode for intermediate-temperature SOFCs (IT-SOFCs).