Preparation And Properties Of SrFeO₃ Anode Materials Doped By Transition Metal

Solid oxide fuel cells（SOFC）can convert the chemical energy of fuel into electrical energy through an electrochemical process.It has the advantages of high energy conversion efficiency,clean and pollution-free,which is conducive to implementing the energy conservation and environmental protection strategy vigorously promoted by the state.However,the traditional Ni/YSZ anode materials are prone to cause the occurrence of carbon deposition when working under hydrocarbon fuel gas,resulting in rapid degradation of battery performance.Perovskite materials have attracted extensive attention because of their excellent performance of carbon resistance.Among them,Sr Fe O₃-based material can not only adapt to a wide range of oxygen non-stoichiometric ratio,which is conducive to the design of doping ratio of the parent material,but also shows good catalytic activity at high temperature.In this paper,perovskite SrFeO₃ is selected as the parent,and the influence of doping on its phase structure,electrical and electrochemical properties is studied by doping transition metal at its B-site,in order to obtain SOFC anode material with high catalytic performance.The main work is as follows:The material of SrFe_1-xNi_xO_3-δ（x=0,0.05,0.10,0.15）doped with Ni was prepared.It is found that a single cubic perovskite structure can be obtained from all samples sintered at1200℃in air for 10 hours.After the reduction at 850℃and 5%H₂/Ar,the main phase of the sample becomes to be Sr₂Fe₂O₅,and the Ni-doped sample has the dissolution of Fe-Ni nanoparticles.The electrochemical performance test results show that Sr Fe_0.95Ni_0.05O_3-δ（SFN5）has the best performance in the samples doped with different content of Ni.The polarization impedance of half cell at 850℃is 0.19Ωcm²,and the peak power density of single cell at 850℃is 536 m W cm^-2.In methane atmosphere,the peak power density is 259m W cm^-2 at 900℃,showing a good performance of carbon resistance.The samples of SrFe_1-xTa_xO_3-δ（x=0.05,0.10,0.15,0.20）doped with Ta were synthesized.The results show that the Sr Fe_1-xTa_xO_3-δ（x=0.05,0.10,0.15,0.20）samples sintered at 1350℃for 10 hours all have cubic perovskite structure.After reduction at850℃and 5%H₂/Ar,the structure of the sample remains a single cubic perovskite structure.The conductivity test results show that SFT10 sample has the highest conductivity under hydrogen.The electrochemical test results show that SFT10 has the best performance.The polarization impedance of the half cell with SFT10 as the electrode material is 0.44Ωcm² and the peak power density of a single cell is 793 m W cm^-2 at 850℃in hydrogen atmosphere.In methane atmosphere,the peak power density reaches 350 m W cm^-2 at 900℃,and there is no obvious attenuation when working for 30 hours at 800℃.Based on SrFe_0.9Ta_0.1O_3-δ,we prepared Sr_1-xFe_0.9Ta_0.1O_3-δ（x=0.02,0.04,0.06）electrode materials with A-site absence.The electrochemical test results show that the polarization impedance of the half cell prepared with Sr_0.94Fe_0.9Ta_0.1O_3-δ（SFT94）electrode material is 0.171Ωcm² at 850℃,and the peak power density of the single cell is 864 m W cm^-2 at 850℃.In methane atmosphere,the peak power density reached 398 m W cm^-2 at900℃,and the peak power density remained stable when working for 50 hours at 800℃.