Composite electrodes for ceria-carbonate intermediate temperature electrolytes

Composite electrodes based on several ceramic oxides were tested for their chemical compatibility and electrochemical performance in systems based on composite Gd-doped ceria + alkaline carbonate electrolytes. Reactivity tests performed at 700 °C (accelerated testing conditions), involving the ceramic electrode materials and one mixture of Na and Li carbonates, identified two promising perovskyte-type ceramics, LaCoO3 and La0.8Sr0.2Co0.2Fe0.8O3, as the most stable. Co-pressed and co-sintered cell assemblies (electrode/electrolyte/electrode) involving composite electrodes (perovskytes mixed with alkaline carbonates) were studied in detail by scanning electron microscopy and tested by impedance spectroscopy in air in the temperature range 300–600 °C. These tests showed the potential of these composite electrodes for intermediate temperature applications, clearly surpassing in performance standard Au electrodes, here used as reference.

► Ceramic perovskytes tested in composite cathodes for ceria-carbonate electrolytes.
► High chemical stability demonstrated in contact with molten carbonates.
► Co-pressing and co-firing yielded good electrode/electrolyte bonding.
► Ceramic based composite electrodes performed better than gold electrodes.