Hetero-structured composite cathodes by electrospinning with high CO2-poisoning tolerance for solid oxide fuel cells

Abstract

The sluggish oxygen reduction reaction (ORR) kinetics significantly hinder the development of intermediate temperature solid oxide fuel cells (IT-SOFC). Herein, a heterostructure composite fibers cathode composed of Ba0.9La0.1Co0.7Fe0.2Nb0.1O3-δ and Sm0.2Ce0.8O2-δ (BLCFN-SDC fibers) has been co-synthesized by electrospinning method, which exhibited excellent electrochemical activity, CO2 tolerance and long-term stability. The polarization resistance (Rp) of BLCFN-SDC fibers cathode at 700 °C is only 0.050 Ω cm2, much lower than those of single-phase BLCFN fibers (0.069 Ω cm2) and BLCFN powders (0.073 Ω cm2). Such improvement can be attributed to the extended three-phase boundary (TPB) and more exposed oxygen reduction reaction (ORR) active sites. Besides, the unique fibers structure provides continuous charge transport paths, which improve its conductivity. Furthermore, BLCFN-SDC fibers exhibits excellent CO2 tolerance in high concentration CO2 atmosphere, benefited from the low CO2 adsorption characteristics and stability of SDC. The results suggest that such heterostructure fibers cathode with excellent ORR activity and CO2 durability might provide a novel method to design efficient catalysts for SOFCs and other energy conversion devices.