Research On Cathode Material Properties Of No Co-based Solid Oxide Fuel Cells

At present,human beings are facing two major challenges of energy crisis and environmental pollution.It is urgent to explore efficient and clean energy technologies.Solid oxide fuel cells?SOFCs?are characterized by the high energy conversion efficiency and cleanliness.Conventional cathode materials?LSM,etc.?have only stable electrochemical properties at high temperatures?>800??,low temperature can significantly reduce their oxygen ion conductivity and catalytic activity,and high temperature operation can cause equipment maintenance costs and other shortcomings,to explore cathode materials with superior low and medium temperature performance have now become the mainstream trend.In this paper,the crystal structures of Sr_1-xCa_xFe_1-yNb_yO_3-??0?x?1,0?y?1??Ba_0.95Ca_0.05Fe_1-yNb_yO_3-??y=0.05,0.1?and Ba_0.5Sr_0.5Fe_1-ySn_yO_3-??y=0,0.05,0.1?three series of cobalt-free cathode materials carried out research and analysis work,through different proportions of Ca?Nb and Sn elements doping,at the same time carried out the relevant performance tests to explore its feasibility as a cathode material.Sr_1-xCa_xFe_1-yNb_yO_3-??0?x?1,0?y?1?cathode materials were prepared by solid-state reaction.Through the XRD patterns,we can see that SrFeO_3-?and Sr_0.76Ca_0.24FeO_3-?appear weak miscellaneous peaks,Sr_0.76Ca_0.24Fe_0.9Nb_0.1O_3-?and Sr_0.76Ca_0.24Fe_0.95Nb_0.05O_3-?samples formed pure cubic perovskite structure.and we found that when the doping proportion of Nb in B site increases,the angle of diffraction angle becomes smaller,the TEC value of the material decreases,the conductivity value decreases,and the interface values of Rp increases,which are 0.361?0.037?0.026?0.031?cm² at 800?,respectively.The maximum power density of Sr_0.76Ca_0.24Fe_0.95Nb_0.05O_3-?is 391 mW cm^-2 at 800?.The Ba_0.95Ca_0.05Fe_1-yNb_yO_3-??y=0.05,0.1?series cathode materials were prepared by solid-state reaction method.We found that BaFeO₃ did not form a stable cubic perovskite structure.WhenCaandNbweredoped,Ba_0.95Ca_0.05Fe_0.9Nb_0.1O_3-?and Ba_0.95Ca_0.05Fe_0.95Nb_0.05O_3-?materials all have the cubic phase perovskite structure,but we found that there is heterogeneous BaFe₂O₄.The experimental results show that when the doping amount of Nb increases,the TEC value of the cathode material decreases,the conductivity value decreases,and the interface polarization impedance decreases.The Ba_0.5Sr_0.5Fe_1-ySn_yO_3-??y=0,0.05,0.1?series cathode materials were prepared by solid-state reaction method.The sample of Ba_0.5Sr_0.5FeO_3-??Ba_0.5Sr_0.5Fe_0.9Sn_0.1O_3-?and Ba_0.5Sr_0.5Fe_0.95Sn_0.05O_3-?all formed a single cubic perovskite structure.Through the analysis of experimental results,when the temperature rises to 800?,the polarization impedance can be reduced to 0.069?cm²,the maximum power density can reach 438 mW cm^-2.The results show that Sr_1-xCa_xFe_1-yNb_yO_3-??0?x?1,0?y?1?and Ba_0.5Sr_0.5Fe_1-ySn_yO_3-??y=0,0.05,0.1?are two series oxide Prospects of the cathode material.