Preparation and characterization of La1−xSrxNiyFe1−yO3−δ cathodes for low-temperature solid oxide fuel cells

Perovskite-type La1−xSrxNiyFe1−yO3−δ (x = 0.3, 0.4, 0.5, 0.6, y = 0.2; x = 0.3, y = 0.2, 0.3, 0.4) oxides have been synthesized and employed as cathodes for low-temperature solid oxide fuel cells (SOFCs) with composite electrolyte. The segregation of La2NiO4±δ is observed to increase with the increasing Sr2+ incorporation content according to X-ray diffraction (XRD) results. The as-prepared powders appear porous foam-like agglomeration with particle size less than 1 μm. Maximum power densities yield as high as 725 mW cm−2 and 671 mW cm−2 at 600 °C for fuel cells with the LSNF4628 and LSNF7337 composite cathodes. The maximum power densities continuously increase with the increasing Sr2+ content in LSNF cathodes, which can be mainly ascribed to the possible charge compensating mechanism. The maximum power densities first increase with the Ni ion incorporation content up to y = 0.3 due to the increased oxygen vacancy, ionic conductivity and oxygen permeability. Further increase in Ni ion content results in a further lowering of fuel cell performance, which can be explained by the association of oxygen vacancies and divalent B-site cations in the cathode.