Compositional Improvement of Ln[sub 0.435]Ba[sub 0.145]Sr[sub 0.4]Fe[sub 0.8]Co[sub 0.2]O[sub 3−δ] IT-SOFC Cathodes Performance by Multiple Lanthanide Substitution

A series of materials based on the perovskite Ln 0.435 Ba 0.145 Sr 0.4 Fe 0.8 Co 0.2 O 3 − δ system ( Ln = La 1 − x − y Pr x Sm y ) has been characterized as intermediate temperature solid oxide fuel cell (IT-SOFC) cathodes. Among the different La, Pr, and Sm combinations, those containing at a time Sm and La or alternatively Pr and La show the lowest polarization resistance values. Within the same substitution degree, praseodymium-based compositions have lower electrode resistance than samarium-based ones. Promising electrode compositions based on different ratios of Pr and La were tested in fully assembled fuel cells, comprising a Ni–yttria-stabilized zirconia (YSZ) anode and a YSZ/gadolinium-doped ceria bilayered electrolyte, and they were compared to a cell with a Pr 0.58 Sr 0.4 Fe 0.8 Co 0.2 O 3 − δ cathode. A maximum power density of 0.45 W cm − 2 was achieved at 650 ° C for the most promising La 0.2175 Pr 0.2175 Ba 0.145 Sr 0.4 Fe 0.8 Co 0.2 O 3 − δ cathode-based fully assembled fuel cell. A systematic electrochemical study based on electrochemical impedance spectroscopy is shown for the fully assembled cells as a function of p H 2 , p O 2 , applied current, and operating temperature.