Assessment of Nd1.5Pr0.5Ni1-xMxO4+δ (M = Cu, Co, Mo; x=0, 0.05 and 0.1) as cathode materials for intermediate-temperature solid oxide fuel cell

This work presents study of the doping effect of M = Cu, Co, and Mo on the cathode properties of Nd1.5Pr0.5Ni1-xMxO4+delta. In particular, four compositions are prepared by a modified sol-gel method, e.g., Nd1.5Pr0.5NiO4+delta (NPN), Nd1.5Pr0.5Ni0.9Cu0.1O4+delta (NPNCu), Nd1.5Pr0.5Ni0.9Co0.1O4+delta (NPNCo), and Nd1.5Pr0.5Ni0.95Mo0.05O4+delta (NPNMo). The crystal structure, phase stability, electrical conductivity, thermal expansion coefficient (TEC), and electrochemical performance of the oxides are systematically investigated. No chemical reactions between NPN, NPNCu, NPNCo, and NPNMo cathodes and Ce0.8Sm0.2O1.9 electrolyte are found. The average TEC values of the NPN, NPNCu, NPNCo, and NPNMo are determined to be 13.9 x 10(-6) K-1, 13.6 x 10(-6) K-1, 14.7 x 10(-6) K-1, and 13.2 x 10(-6) K-1 in the range of 30-1000 degrees C, close to that of the typical electrolyte materials. NPN and NPNCu cathodes exhibit very low interfacial polarization resistance value of 0.033 and 0.032 Omega cm(2) at 800 degrees C, which translates to superior fuel cell performance, e.g., peak power density of 456 and 443 mW cm(-2), respectively. The electrochemical performance, however, could be significantly degraded by the Co and Mo doping in the Ni site. The presented results demonstrate that NPN and NPNCu are promising cathode candidate for intermediate-temperature solid oxide fuel cells.