Enhanced oxygen reduction reaction kinetics in nanocrystalline IT-SOFC cathodes

BAQUÉ, LAURA; SOLDATI, ANALIA L.; TROIANI, HORACIO; SCHREIBER, ANJA; CANEIRO, ALBERTO; SERQUIS, ADRIANA C.

Okinawa

Simposio; SOFC XIII, 13th International Symposium on Solid Oxide Fuel Cells; 2013

Tohoku University

Solid oxide fuel cell performance is usually limited by high cathodic area specificresistance (ASR) at intermediate temperatures (500-700°C). ASR can be decreased byreducing the particle size to nanometer range. This improvement is usually ascribed to thearea/volume ratio increase and a higher concentration of active sites for the oxygenreduction reaction (ORR). Nevertheless, this solely explanation seems not to be enough forexplaining the high electrochemical performance of some nanostructuredLa0.4Sr0.6Co0.8Fe0.2O3-d cathodes previously reported [Baqué et al, Electrochemistry Comm.10 (2008) 1905-1908]. Accordingly, the ORR of these cathodes was studied byelectrochemical impedance spectroscopy (EIS) in air and in pure oxygen within the 400-700°C range. The nanostructure was characterized even at atomic level by transmissionelectron microscopy, revealing that the cathode is composed of nanocrystals surrounded byzones with some degree of crystalline disorder. These results suggest that this kind ofnanostructure facilitate the ORR in this compound.