Effects Of Co-doped Barium Cerate Additive On Performances Of Samarium Doped Ceria Electrolyte For IT-SOFCS

Solid Oxide Fuel Cell（SOFC）is a type of power generation system that converts chemical energy in fuels directly into electricity.It received worldwide attention due to its high conversion efficiency,fuel flexibility and low pollutant emission.However,conventional SOFC needs to work at high temperature（over 800oC）,which limited its commercialization.To lower its working temperature to an intermediate range（IT,500-800oC）,appropriate electrolyte and electrode materials with higher electrical conductivity should be developed first.Conventional electrolyte material is doped zirconia（YSZ）,whose conductivity becomes low at IT range.Newly developed doped ceria materials have higher electrical conductivity,while they exhibit significant electronic conductivity in the anode working atmosphere of SOFC,which decreases the efficiency of SOFC and limits their application in SOFC.A novel Sm_0.2Ce_0.8O_2-δbased electrolyte with BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3-δaddition（15:85and 30:70wt%）,designated as B15S85 and B30S70,is prepared by mechanical mixing for intermediate-temperature solid oxide fuel cell（IT-SOFC）.Their performances were investigated comparatively with single phase SDC and BZCYYb.Physical characterization identified elements diffusion between two phases in B15S85 and B30S70,as well as decreased average grain size and improved relative density compared to SDC.Their electrical conductivity determined from electrochemical impedance spectra in wet air was0.017,0.013Scm^-1 at 600oC respectively,higher than the 0.011 and 0.009Scm^-11 for SDC and BZCYYb.By contrast,their total conductivity was significantly lower than SDC in wet5%H₂-N₂ and H₂.Single cell with B15S85 as electrolyte exhibited improved OCV than SDC based cell,much lower electrode polarization resistance（0.758Ωcm² at 500oC）and encouraging high power density（0.891W/cm² at 650oC）compared to the SDC and BZCYYb cells,with SDC-La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ（LSCF）cathode and NiO-SDC anode prepared by the same method.