High-temperature Electrochemical Performance Of SrFeO_3-?-based Mixed Conductor Cathode Materials

In this study,SrFe_1-xCu_xO_3-?,SrFe_1-xNi_xO_3-?and SrFe_1-xSn_xO_3-?series materials were synthesized,and their performance as cathode materials of medium temperature solid oxide fuel cell(IT-SOFC)was investigated in detail.The specific research results are as follows:First,SrFe_1-xCu_xO_3-?(x=0-0.3)cathode powders were synthesized by glycine-nitrate combustion method.XRD patterns of SrFe_1-xCu_xO_3-?(x=0.1-0.3)show that all the samples are single cubic perovskite materials.The XRD pattern of SrFe O_3-?show that is tetragonal phase structure.The conductivity relaxation test proves that the higher the doping amount of Cu,the larger the D_chem and k_chem values of the material.SrFe_0.7Cu_0.3O_3-?shows the best catalytic performance for oxygen reduction reaction.The polarization resistance is 0.107?cm²,and the peak power density reaches 0.85 W cm^–2 at 700°C.Furthermore,the charge transfer process is identified to be the rate control step of ORR reaction on this cathode.Finally the first-principles computation result confirms that introducing Cu reduces the formation energy of oxygen vacancies,which yields favorable conditions for producing oxygen vacancy in Cu-doped SrFe O₃.SrFe_1-xNi_xO_3-?(x=0.1-0.2)cathode powders were synthesized by glycine-nitrate combustion method.XRD patterns of SrFe_1-xNi_xO_3-?show that all the samples are single cubic perovskite materials.The results of electrical conductivity tests show the electrical conductivity in SrFe_1-xNi_xO_3-?increase with the increase of Ni content,and the peak conductivity value of SrFe_0.8Ni_0.2O_3-?is 399.7 S cm^-1.SrFe_0.8Ni_0.2O_3-?has the best catalytic performance for oxygen reduction,with a polarization resistance of 0.093?cm² and it's electrolyte support cell Ni O-YSZ|CGO|SrFe_0.8Ni_0.2O_3-?has an output power density of 0.30 W cm^-2at 700°C.The rate control step of the ORR reaction on the SrFe_0.8Ni_0.2O_3-?cathode is the charge transfer reaction at the three-phase interface.SrFe_1-xSn_xO_3-?(x=0.05-0.15)perovskite oxides were prepared by glycine combustion method.XRD patterns of SrFe_1-xSn_xO_3-?show that all the samples are single cubic perovskite materials.The results of electrical conductivity tests show that with the increase of the content of Sn,the conductivity increasing,and the peak conductivity of SrFe_0.85Sn_0.15O_3-?is 29.6 S cm^-1.Among the SrFe_1-xSn_xO_3-?materials,SrFe_0.95Sn_0.05O_3-?has the best catalytic performance for oxygen reduction,with a polarization resistance of 0.12?cm²and it's electrolyte support cell Ni O-YSZ|CGO|SrFe_0.95Sn_0.05O_3-?has an output power density of 0.28 W cm^-2 at700°C.The rate control step of ORR reaction on SrFe_0.95Sn_0.05O_3-?cathode is the diffusion of oxygen in the porous electrode.