The Electrocatalytic Performance Of The Iron-based Perovskite Fuel Cell Ba_0.95La_0.05FeO_3-δ Cathode Catalyst

Intermediate temperature solid oxide fuel cells（IT-SOFCs）have received widespread attention because of their non-pollution and high energy conversion efficiency.Mixed ionic-electronic conductivity（MIEC）materials are promising oxygen reduction cathodes for solid oxide fuel cells（SOFC）.In this paper,the mixed ionic-electronic conductor（MIEC）Ba_0.95La_0.05Fe O_3-δ（BLF）with perovskite structure is used as the research object,doping B-site with low-valent metal ions(Cu²⁺/Zn²⁺)and high-valent metal ions(Ta⁵⁺)of different transition metals,respectively.We has successfully synthesized Ba_0.95La_0.05Fe_1-xCu_xO_3-δ,Ba_0.95La_0.05Fe_1-xTa_xO_3-δand Ba_0.95La_0.05Fe_1-xZn_xO_3-δseries cathode materisls,and detailed structural characterization and electrochemical properties were studied.The main research contents are as follows:The cathode material Ba_0.95La_0.05Fe_1-xCu_xO_3-δ（x=0.05,0.10,0.15）were synthesized by the traditional high-temperature solid-state method.XRD results show that the Cu doping forms a cubic symmetrical perovskite oxide Ba_0.95La_0.05Fe_1-xCu_xO_3-δwith space group Pm3m.All materials and electrolyte Ce_1.9Gd_0.1O_1.95（CGO）are sintered at high temperature for a long-time,they show good high-temperature chemical compatibility and do not occur chemical reaction.The introduction of Cu increased the oxygen vacancy concentration of Ba_0.95La_0.05Fe O_3-δmaterial and increased its electrical conductivity,reaching the maximum electrical conductivity value of 28.25 S cm^-1at450°C.At 700°C,the polarization resistance of the Ba_0.95La_0.05Fe_0.85Cu_0.15O_3-δ（BLFC015）cathode is 0.091Ωcm²,and the power density of the single cell with the BLFC015 cathode is 1.05 W cm^-2under an output voltage of 0.53 V.Under the conditions of different CO₂concentration tests,the BLFC015 cathode showed satisfactory CO₂tolerance and chemical stability.These results indicate that Ba_0.95La_0.05Fe_1-xCu_xO_3-δseries cathode is a promising IT-SOFCs cathode.The cathode material Ba_0.95La_0.05Fe_1-xTa_xO_3-δ（x=0.1,0.2）was synthesized by the traditional high-temperature solid-state method,and their practical application as IT-SOFCs cathode materials were systematically evaluated.The results show that a small amount of Ta doping can effectively stabilize the cubic perovskite structure of Ba_0.95La_0.05Fe O_3-δmaterial,and improve the ORR electrocatalytic performance.Among them,Ba_0.95La_0.05Fe_0.9Ta_0.1O_3-δ（BLFT010）cathode has the most outstanding electrochemical performance,the lowest polarization resistance is 0.133Ωcm²at700°C,and the peak power density ofsinglecell with BLFT010 cathode is 751.7 m W cm^-2.In addition,the BLFT010 cathode exhibited excellent CO₂tolerance performance under the conditions of different CO₂concentration tests.The cathode materials Ba_0.95La_0.05Fe_1-xZn_xO_3-δ（x=0.05,0.10,0.15）were synthesized by sol-gel method.The study found that Zn²⁺doping effectively stabilized the cubic phase structure of Ba_0.95La_0.05Fe O_3-δmaterial.Electrochemical test results show that the Ba_0.95La_0.05Fe_0.9Zn_0.1O_3-δ（BLFZ010）cathode has the most outstanding electrochemical performance,with a minimum polarization resistance of 0.109Ωcm²at700℃,the peak power density of electrolyte-supported single cell with BLFZ010cathode is 274.9 m W cm^-2and has excellent long-term stability.