BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) as cathode material for intermediate temperature solid oxide fuel cells

摘要

BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) (BCFN) has been synthesized and characterized as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) using La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(3-δ) (LSCM) electrolyte. X-ray diffraction results show that pure cubic BCFN perovskite phase can be obtained at 950 C through solid state reactions of BaCO_3, CO_3O_4, Fe_2O_3 and Nb_2O_5. The electrical conductivity of BCFN increases with the increase in oxygen partial pressure, indicating that BCFN is a p-type semiconductor. The polarization resistance of the BCFN cathode with LSGM electrolyte is only 0.06 Ω cm~2 at 750 C in air under open-circuit conditions. The overpotential at a current density of 1 A cm~-2 in oxygen was only about 0.04 V at 750 C. Peak power densities of 550,770 and 980mWcm_2 have been achieved on LSGM-electrolyte supported single cells with the configuration of Ni-Gd_(0.1)Ce_(0.9)O_(1.95)|La_(0.4)Ce_(0.6)O_2|LSGM|BCFN at 700, 750 and 800 C, respectively. These results indicate that BCFN is a very promising cathode candidate for IT-SOFCs with LSGM electrolyte.