Preparation and evaluation of a stable cathode material SmBa0.75Sr0.25Fe2O5+δ for solid oxide fuel cells

Abstract In this study, Sr doping SmBa0.75Sr0.25Fe2O5+δ (SBSF25) oxide for solid oxide fuel cells (SOFCs) cathode are prepared and investigated its properties. First principles calculation indicates that the oxygen vacancy formation energy of SBSF25 (1.76 eV) is lower than that of SmBaFe2O5+δ (2.49 eV). Doping Sr significantly reduces the band center energy of Fe-3d and O-2p in SBSF25. At 800 ℃, the polarization resistance (Rp) of SBSF25 on SDC and LSGM electrolyte are 0.025 Ωcm2, and 0.018 Ωcm2 in air, respectively. While the Rp of SBF on on SDC and LSGM electrolyte are 0.064Ωcm2, and 0.046Ωcm2 in air, respectively. At 800 ℃, using H2 as fuel, the maximum power density (MPD) of fuel cell with SBSF25, SBF as cathode reaches 758.6 mW/cm2 and 670.2mW/cm2, respectively. Sr doping SBF significantly improves the Rp stability in air and containing CO2 atmosphere. This results indicated that SBSF has good electrochemical performance and stability as intermediate temperature SOFCs cathode.