Composite cathode Bi_1.14Sr_0.43O_2.14-Ag for intermediate-temperature solid oxide fuel cells

Abstract

Composites consisting of strontium stabilized bismuth oxide (Bi_1.14Sr_0.43O_2.14, SSB) and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There were no chemical reactions between the two components. The microstructure of the interfaces between composite cathodes and Ce_0.8Sm_0.2O_1.9 (SDC) electrolytes was examined by scanning electron microscopy (SEM). Impedance spectroscopy measurements show that the performance of cathode fired at 700 °C is the best. When the content of Ag₂O is 70 wt%, polarization resistance values for the SSB-Ag cathodes are as low as 0.2 Ωcm² at 700 °C and 0.29 Ωcm² at 650 °C. These results are much smaller than some of other reported composite cathodes on doped ceria electrolyte and indicate that SSB-Ag composite is a potential cathode material for intermediate temperature SOFCs.

Keywords

solid oxide fuel cells (SOFCs) / composite cathode / strontium stabilized bismuth oxide (SSB) / samaria doped ceria (SDC)

References

[1] Jiang S. P., Leng Y. J., Chan S. H., . Development of (La, Sr)MnO₃-based Cathodes for Intermediate Temperature Solid Oxide Fuel Cells[J]. Electrochem. Solid State Lett., 2003, 6(4): A67-A70.

[2] Minh N. Q. Ceramic Fuel Cells[J]. J. Am. Ceram. Soc., 1993, 76(3): 563-588.

[3] Steele B. C. H. Appraisal of Ce_1−yGd_yO_2−y/2 Electrolytes for IT-SOFC Operation at 500 Degrees C[J]. Solid State Ionics, 2000, 129(1–4): 95-110.

[4] Sammes N. M., Tompsett G. A., Nafe H., . Bismuth Based Oxide Electrolytes-Structure and Ionic Conductivity[J]. J. European Ceram. Soc., 1999, 19(10): 1 801-1 826.

[5] Boivin J. C., Mairesse G. Recent Material Developments in Fast Oxide Ion Conductors[J]. Chem. Mat., 1998, 10(10): 2 870-2 888.

[6] Xia C. R., Zhang Y., Liu M. L. Composite Cathode Based on Yttria Stabilized Bismuth Oxide for Low-temperature Solid Oxide Fuel Cells[J]. Appl. Phys. Lett., 2003, 82(6): 901-903.

[7] Zhang J. D., Ji Y., Gao H. B., . Composite Cathode La_0.6Sr_0.4Co_0.2F_e0.8O₃-Sm_0.1Ce_0.9O_1.95-Ag for Intermediatetemperature Solid Oxide Fuel Cells[J]. J. Alloy. Compd., 2005, 395(1–2): 322-325.

[8] Hwang H. J., Moon J. W., Moon J. Removal of Nitric Oxide (NO) by Perovskite-type Composite Catalytic Thick Film, La_0.6Sr_0.4Co_0.2Fe_0.8O₃-delta and Gadolinia-doped Ceria Electrolyte Gd_0.2Ce_0.8O₂-delta[J]. J. Am. Ceram. Soc., 2005, 88(1): 79-84.

[9] Hwang H. J., Ji-Woong M., Seunghun L. Electrochemical Performance of LSCF-based Composite Cathodes for Intermediate Temperature SOFCs[J]. J. Power Sources, 2005, 145(2): 243-248.

[10] Shao Z. P., Haile S. M. A High Performance Cathode for the Next Generation of Solid Oxide Fuel Cells[J]. Nature, 2004, 431(7005): 170-173.

[11] Xu X. Y., Xia C. R., Mao G. L., . Fabrication and Performance of Functionally Graded Cathodes for IT-SOFCs Based on Doped Ceria Electrolytes[J]. Solid State Ionics, 2005, 176(17–18): 1 513-1 520.

[12] Dusastre V., Kilner J. A. Optimisation of Composite Cathodes for Intermediate Temperature SOFC Applications[J]. Solid State Ionics, 1999, 126(1–2): 163-174.