THE INFLUENCE OF LOW OPERATING TEMPERATURE ON MOLTEN-CARBONATE FUEL-CELLS DECAY PROCESSES

Investigations have been carried out to study the influence of low ope rating temperature (873 K) on the decay mechanisms that affect the end urance of a molten carbonate fuel cell. An experiment has been perform ed for several thousands of hours of continuous operation at a current density of 160 mA cm(-2) on a bench-scale cell to evaluate the electr ochemical performance parameters and morphological characteristics of spent components. The tested components were a traditional LiAlO2 matr ix, charged by a mixture of Li/K, NiO cathode and Ni/Cr anode. During the test, measurements of temperature, pressure, flows, cell internal resistance, current and voltage have been taken continuously, as well as gas chromatography analyses. At the end of the experiment, the cell showed an increase in internal resistance of 0.376 Omega cm(-2) and a lowering of open-circuit voltage of 30 mV. The electrolyte distributi on in the components indicated an excess of empty pores in the tile st ructure with a filling degree of 72.8%. By contrast, the anode retaine d a filling degree of 64.3%, while the cathode appeared under partial flooding condition with a filling degree of 48.2%. The SEM cross-secti on view of the cell package (cathode, tile and anode) showed evidence of a process of cathode dissolution and coprecipitation of Ni in a nar row band located almost in the middle of the section. The Ni, Cr, Al a nd K distribution profiles in the cross-section were investigated by E DAX analysis. (C) 1997 by John Wiley & Sons, Ltd.