Coking-Resistance and Sulfur-Tolerance Study of La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ Anode

Solid oxide fuel cell (SOFC) has experienced a growing interest in the last few decades because of generating energy more efficiently than the conventional combustion of fossil fuels. By using the same material as anode and cathode of symmetric solid oxide fuel cell (SSOFC), the production of reliable and repeatable cells would be simpler. In this work, La_0.4Sr_0.6Co_0.2Fe_0.7Nb_0.1O_3-δ (LSCFN) has been investigated firstly as potential cathode material for SOFC. The cathode polarization resistances are only 0.1 Ω cm² at 800 ^oC. The stability of phase structure, electrode microstructure and polarization resistances for the LSCFN in the atmosphere of air have been studied. Then, LSCFN have been investigated as potential anode material for SOFC. The results show that LSCFN have high catalytic activity in methane catalytic combustion reaction, the total conversion temperature of 1% CH₄ using LSCFN as catalyst was as low as 650 ^oC. The performance of carbon-resistance and sulfur-tolerance in SOFC were studied using LSCFN ceramic anode with La_0.8Sr_0.2Ga_0.83Mg_0.17O_3-δ (LSGM) electrolyte. Long-term operation of such single cell under methane lasted for 120 hours without degradation. The output power density fueled with H₂-50 ppm H₂S was stable enough in 120 hours’ operation which indicated a good sulfur-tolerant performance. Finally, the maximum power densities generated by the SSOFC cell with LSCFN electrode are 650 mW cm^-2 in H₂, and the cell maximum power output has demonstrated to be not affected by the redox cycling of the anode during a total of 21 cyclic testing, indicating that the LSCFN has excellent redox stability. All of these results indicate that LSCFN can potentially be a promising candidate for the electrode material of SSOFC.