Study On Modification And Electrochemical Properties Of BaFeO_3-? Cathode Material For Solid Oxide Fuel Cells

Fuel cells gain extensive attention because they can directly convert chemical energy into electrical energy in a clean and high efficiency way.They can be widely used in portable electronics,general household power supplies,power vehicles and so on.The cathode materials BaFe_1-xCu_xO_3-??x=0,0.10,0.15,0.20 and 0.25,abbreviated as BFC-0,BFC-10,BFC-15,BFC-20 and BFC-25,respectively?were prepared by a combined EDTA-citrate complexing sol-gel method.XRD results show that the BFC-0 displays the rhombohedral structure and BFC-x?x=10,15,20 and 25?exhibit cubic structure with the space group of Pm3m?221?.The substitution of Fe by Cu increases the thermal expansion coefficient?TEC?.The average TEC increases from 18.8×10^-6 K^-1 for BFC-0 to 22.9×10^-6 K^-1 for BFC-20 in the temperature range of30-850?C.The electrical conductivity of BFC-x?x=0,10,15,20 and 25?are relatively low.But all the samples exhibit excellent electrochemical performances.The polarization resistance of BFC-20 is 0.014?cm² at 800?C.The power density of the single fuel cell is 572.0 m W cm^-2 at 800?C.Ba Fe_0.8Cu_0.2O_3-?-xCe_0.8Sm_0.2O_1.9?BFC-xSDC?composite cathodes were prepared.XRD results show that BFC is chemically compatible with the electrolyte SDC.The thermal expansion coefficient decreases with the increase of SDC content.However,the addition of SDC increases the electrical conductivity.The addition of SDC increases the electrochemical performances.The polarization resistance of 0.01?cm² is achieved at 800°C for the BFC-30SDC composite cathode.At the same time,the BFC-30SDC composite cathode delivers the highest power density of 644.9mW cm^-2 at 800°C.