Significant promotion of ORR activity for Ca₃Co₄O₉₊ cathode by reaction product of electrode and electrolyte

Ca3Co4O9+delta (CCO) cathode has been extensively studied for its excellent thermal expansion matching with commonly used electrolytes. CCO composite cathode with different concentrations of La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) was prepared to evaluate its performance on LSGM electrolyte in this work. The appropriate amount of LaCoO3 generated by the in-situ reaction of CCO and LSGM under operating conditions significantly enhances the oxygen exchange ability of CCO cathodes. The composite cathode containing 60 wt. % CCO and 40 wt. % LSGM (C-LGM60) exhibits the best electrochemical performance and the lowest polarization impedance among the C-LGM series cathodes. The area-specific resistance (ASR) of C-LGM60 is 0.06 Omega cm(2) at 750 degrees C. The maximal power density of the electrolyte-supported cell with C-LGM60 cathode reaches 489 mWcm(-2) at 800 degrees C. After a 10 h stabilizing, there is no observable decline of the cell during the next 40 h of discharge. These results encourage the research of using CCO cathode on LSGM electrolytes and make valuable improvements on the development of SOFC cathode.