One-pot synthesized hetero-structured Ca3Co2O6/La0.6Ca0.4CoO3 dual-phase composite cathode materials for solid-oxide fuel cells

• Hetero-structured (1−x)Ca3Co2O6/x(La0.6Ca0.4)2Co2O6 dual-phase composites are attained by one-pot synthesis.
• The dual-phase composites are evaluated as cathode materials for solid-oxide fuel cells.
• Greatly improved electrochemical performance is resulted from the synergistic effect.
• A power density of 620 mW cm−2 is achieved at 800 °C.

To provide hexagonal Ca3Co2O6 with better electrochemical performance as cathode material for solid-oxide fuel cell, Ca-doped LaCoO3 perovskite is introduced as the second phase to achieve hetero-structured (1−x)Ca3Co2O6/x(La0.6Ca0.4)2Co2O6 dual-phase composites. The composites are successfully synthesized via a simple one-pot method. They behave as thermal-activated semiconductors in the temperature range from 300 to 800 °C, and the electrical conductivity is progressively enhanced with increasing x. Electrochemical measurements indicate that the composite electrodes exhibit reduced area specific resistance, and the x = 0.5 composite cathode shows the lowest polarization behavior. A power density as high as 620 mW cm−2 is attained at x = 0.5 measured at 800 °C on an electrolyte-supported single cell with pure H2 as fuel. The improved performance in the dual-phase composite cathode can be ascribed to the enhanced conductivity and enlarged triple-phase boundary region for electrode reaction due to the presence of second phase.

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