Enhancement of cell performance using a gadolinium strontium cobaltite coated cathode in molten carbonate fuel cells

To enhance cathode performance, gadolinium strontium cobaltite (Gd0.6Sr0.4CoO3, GSC) is coated onto a porous Ni plate by a vacuum suction method, for use as the cathode in molten carbonate fuel cells (MCFCs). GSC is a mixed ionic and electronic conductor (MIEC) material, and thus has high electronic conductivity and catalytic activity at low temperatures. The electrode performance of the GSC-coated cathode is examined by various methods, such as single cell operation and electrochemical impedance spectroscopy (EIS). At 600 °C, the performance of a single cell using a GSC-coated cathode is 0.813 V. This result is very surprising given that the performance of an uncoated conventional cathode is 0.69 V. Impedance analysis confirms that a dramatic decrease in the charge transfer resistance after GSC coating is primarily responsible for the cell enhancement at low temperature. The reaction orders for O2 and CO2 at uncoated and GSC-coated cathodes are also examined via a symmetric cell test, to identify the reaction mechanism of oxygen reduction. The peroxide mechanism, which is known to be a fast reaction, is predominant for the GSC-coated cathode at low temperatures, whereas the superoxide mechanism is predominant for the uncoated cathode.

► Preparation of Gd0.6Sr0.4O3-coated cathode for molten carbonate fuel cells.
► Enhancement of cell performance using the modified cathode at low temperatures.
► Decrease of charge transfer resistance after Gd0.6Sr0.4O3 coating.
► The reaction orders of the oxygen reduction reaction at modified cathode.
► Peroxide mechanism, fast reaction, is predominant in Gd0.6Sr0.4O3-coated cathode.