Preparation And Electrochemical Performance Of Novel Mo And Mn Based Cathode Materials In SOFC

Solid oxide fuel cells?SOFCs?,as a new type of green power generation device,have lots of advantages,such as high energy conversion efficiency,wide fuel and environment-friend,attracting many researchers'attention.Among the factors affect the performance of the cell,the performance of the cell electrode material is a major one.The cathode material,as an important part of the single cell,has a great influence on the electrochemical performance of SOFC.Sr₂Fe_1.5-xSc_xMo_0.5O_6-??SFSc_xM,x=0,0.05,0.10?perovskite cathode materials are prepared by partly changing the Fe element in the B site of Sr₂Fe_1.5Mo_0.5O_6-??SFM?oxide with Sc element.The phase structure,microstructure,electrical conductivity test,polarization impedance under different oxygen partial pressure and discharge test performance are systematically investigated.The phase structure of the material is not changed by doping the Sc element.As a result,SFSc_0.05M shows the highest electrical conductivity of 27.8 S cm^-1,and lowest polarization resistance of0.12?cm² at 800?.The key rate limiting step of the SFSc_0.05M cathode in the oxygen reduction reaction is determined by testing the electrochemical impedance pectroscopy under different oxygen partial pressure.An anode-supported single cell with-SFSc_0.05M cathode exhibits a max power density of 1230 mW cm^-2 at 800?.Above results confirm that SFSc_0.05M is a kind of excellent cathode candidate material for SOFCs.Due to their high conductivity,good chemical stability and suitable thermal expansion coefficient,spinel oxide materials can be used as another kind of ideal cathode materials for SOFCs.CuMn₂O₄,MnCo₂O₄ and NiMn₂O₄ powders are investigated as cathode materials for SOFCs.XRD results show that the abtained materials are spinel structure without any impurity phase.SEM images demonstrate that the powders present evacuation net structure,which increase the specific surface area.CuMn₂O₄ shows a the highest conductivity of 78 S cm^-1at 800?,which is much higher than that of MnCo₂O₄(60 S cm^-1)and NiMn₂O₄(21 S cm^-1).CuMn₂O₄ shows a polarization impedance value of 0.14?cm^-2 at 800 ?,which is lower than that of MnCo₂O₄(0.22?cm^-2)and NiMn₂O₄(0.27?cm^-2).The anode-supported single cells with CuMn₂O₄,MnCo₂O₄ and NiMn₂O₄ cathodes are prepared and tested,revealing the highest power densities of 1456,892 and 865 mW cm^-2 at 800 ?,respectively.