Study Of Perovskite Structure Cathode Material For Intermediate-temperature Solid Oxide Fuel Cells

With the reducing of traditional energy sources,the way of development of new energy use is imminent.The solid oxide fuel cells has attracted people's attention due to the advantages such as the high energy conversion rate and environment-friendly advantages.However,it usually works at about 1000 ? and the deceasing of operating temperature will bring about a sharp decline in catalytic performance.Therefore,it is important to develop cathode materials with excellent properties at medium and low temperatures.In this paper,the cathode materials of LnBa_1-xCa_xFe₂O_6-??Ln = La,Pr,Nd;x = 0,0.5??Sr₂Fe_2-x?Ti0.5Mo0.5?xO6-??x = 0.5⁰.7?and Sr₂Fe_1.5Mo_0.5-xIn_xO_6-??x = 0⁰.2?were prepared in order to improve the catalytic activity of the materials by the doping of the elements,and obtain the cathode materials with excellent electrochemical properties.Sr₂Fe_2-x?Ti0.5Mo0.5?xO6-??x = 0.5⁰.7?series cathode materials were prepared by solid state reaction method.The XRD results show that the sample forms a stable cubic perovskite structure.With the increasing replacing content of Fe with Ti and Mo,the thermal expansion coefficient?TEC?decreases and the electrical conductivity decreases.The impedance increases,which are 0.058 ? cm2?0.078 ? cm2?0.139 ? cm2 at 800 ?,respectively.The maximum power density of Sr₂Fe1.5?Ti0.5Mo0.5?0.5O6-? is 656 mW cm-2 at 800 ?.The Sr₂Fe_1.5Mo_0.5-xIn_xO_6-??x = 0⁰.2?series cathode materials were prepared by solid-state reaction method.The addition of In improves the thermal expansion coefficient of the material,but also improves the electrical conductivity.The maximum power density of the sample Sr₂Fe1.5Mo0.3In0.2O6-? is 29% higher than that of undoped,which is 495 mW cm-2.In addition,the layered perovskite oxides LnBa_1-xCa_xFe₂O_6-??Ln = La,Pr,Nd;x = 0,0.5?were also used for the study of the properties of the cathode material.The sample LaBa0.5Ca0.5Fe₂O_6-? exhibits the best electrochemical performance.At 800 ?,the impedance is 0.042 ? cm2 and the maximum power density is 686 mW cm-2.The results show that the three series of oxides mentioned above are promising cathode alternative materials.