Triple Perovskite Nd_1.5Ba_1.5CoFeMnO_9-δ-Sm_0.2Ce_0.8O_1.9 Composite as Cathodes for the Intermediate Temperature Solid...

Triple perovskite has been recently developed for the intermediate temperature solid oxide fuel cell (IT-SOFC). The performance of Nd_1.5Ba_1.5CoFeMnO_9-δ (NBCFM) cathodes for IT-SOFC is investigated in this work. The interfacial polarization resistance (R_P) of NBCFM is 1.1273 Ω cm²~0.1587 Ω cm² in the range of 700-800 °C, showing good electrochemical performance. The linear thermal expansion coefficient of NBCFM is 17.40 × 10^-6 K^-1 at 40-800 °C, which is significantly higher than that of the electrolyte. In order to further improve the electrochemical performance and reduce the thermal expansion coefficient (TEC) of NBCFM, Ce_0.8Sm_0.2O_2-δ (SDC) is mixed with NBCFM to prepare an NBCFM-xSDC composite cathode (x = 0, 10, 20, 30, 40 wt.%). The thermal expansion coefficient decreases monotonically from 17.40 × 10^-6 K^-1 to 15.25 × 10^-6 K^-1. The surface oxygen exchange coefficient of NBCFM-xSDC at a given temperature increases from 10^-4 to 10^-3 cm s^-1 over the po2 range from 0.01 to 0.09 atm, exhibiting fast surface exchange kinetics. The area specific resistance (ASR) of NBCFM-30%SDC is 0.06575 Ω cm² at 800 °C, which is only 41% of the ASR value of NBCFM (0.15872 Ω cm²). The outstanding performance indicates the feasibility of NBCFM-30% SDC as an IT-SOFC cathode material. This study provides a promising strategy for designing high-performance composite cathodes for SOFCs based on triple perovskite structures.