Electrode properties of (Pr0.9La0.1)2−x(Ni0.74Cu0.21Al0.05)O4+δ (with x=0, 0.05, and 0.1) as cathodes in IT-SOFCs

Abstract

A Ruddlesden-Popper phase, (Pr0.9La0.1)2−x(Ni0.74Cu0.21Al0.05)O4+δ ((PL)2−xNCA, x = 0, 0.05 and 0.1), is synthesized and characterized for use as a cathode material in intermediate temperature solid oxide fuel cells (IT-SOFCs). The effects of A-site cation deficiency on the thermal expansion coefficient, electrical conductivity, electrochemical properties, and thermal stability are investigated in detail. (PL)2−xNCA and the Ce0.8Sm0.2O1.9 (SDC) electrolyte are chemically compatible at 1000 °C for 5 h. The average thermal expansion coefficient (TEC) values of (PL)2−xNCA range from 14.1 × 10−6 K−1 to 14.5 × 10−6 K−1 for temperatures between 30 and 1000 °C, which is close to that of conventional SOFC electrolyte materials. The (PL)2−xNCA samples were unstable after heating to 700 and 800 °C for 72 h in air. The (PL)1.9NCA cathode had a minimum area specific resistance (ASR) of 0.033 Ω cm2 at 800 °C. When (PL)2.0NCA was used as the cathode material in electrolyte-supported single cells, the single cell reached a maximum power density of 527 mW cm−2 at 800 °C using an SDC electrolyte.