Enhancing Oxygen Reduction Activity and Cr Tolerance of Solid Oxide Fuel Cell Cathodes by a Multiphase Catalyst Coating

Intermediate temperature solid oxide fuel cells (IT-SOFCs) are cost-effective and efficient energy conversion systems. The sluggish oxygen reduction reaction (ORR) and the degradation of cathodes are critical challenges to the commercialization of IT-SOFCs. Here, a highly efficient multiphase (MP) catalyst coating, consisting of Ba1-xCo0.7Fe0.2Nb0.1O3-delta (BCFN) and BaCO3, to enhance the ORR activity and durability of the state-of-the-art lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-delta, LSCF) cathode is reported. The conformal MP catalyst-coated LSCF cathode shows a polarization resistance (R-p) of 0.048 omega cm(2) at 650 degrees C, about one order of magnitude smaller than that of the bare LSCF. In an accelerated Cr-poisoning test, the degradation rate of the catalyst-coated LSCF electrode is 10(-3) omega cm(2) h(-1) (0.59% h(-1)) over 200 h, only one fifth of the degradation rate of the bare LSCF electrode at 750 degrees C. In addition, anode-supported single cells with the MP catalyst-coated LSCF cathode show a dramatically enhanced peak power density (1.4 W cm(-2) vs 0.67 W cm(-2) at 750 degrees C) and increased durability against Cr and H2O. Both experimental results and density functional theory-based calculations indicate that the BCFN phase improves the ORR activity while the BaCO3 phase enhances the stability of the LSCF cathode.

Automated summary

Intermediate temperature solid oxide fuel cells (IT-SOFCs) face challenges due to the sluggish oxygen reduction reaction (ORR) and cathode degradation. A highly efficient multiphase catalyst coating significantly enhances the ORR activity and durability. Experimental results show improved peak power density and increased durability against Cr and H2O. Both the BCFN phase and BaCO3 phase contribute to the improved performance of the LSCF cathode.