The influence of low operating temperature on molten carbonate fuel cells decay processes

Abstract

SUMMARYInvestigations have been carried out to study the influence of low operating temperature (873 K) on the decay mechanisms that affect the endurance of a molten carbonate fuel cell. An experiment has been performed for several thousands of hours of continuous operation at a current density of 160 mA cm\ on a bench-scale cell to evaluate the electrochemical performance parameters and morphological characteristics of spent components. The tested components were a traditional LiAlO matrix, 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 cm\ and a lowering of open-circuit voltage of 30 mV. The electrolyte distribution in the components indicated an excess of empty pores in the tile structure with a filling degree of 72·8%. By contrast, the anode retained a filling degree of 64·3%, while the cathode appeared under partial flooding condition with a filling degree of 48·2%. The SEM cross-section view of the cell package (cathode, tile and anode) showed evidence of a process of cathode dissolution and coprecipitation of Ni in a narrow band located almost in the middle of the section. The Ni, Cr, Al and K distribution profiles in the cross-section were investigated by EDAX analysis.

Using a three-dimensional computational fluid dynamics model and an agglomerate model to investigate the effect of varying agglomerate parameters and output voltages on proton exchange membrane fuel cell performance

“…When these protons and electrons combine with the oxygen present at the cathode's active catalyst, an ORR will eventually occur and produce water. The reaction here at the cathode determines much of the cell's performance, since the ORR at the cathode is significantly slower than the HOR at the anode [ 37 , 38 ].…”

Influence of Anode Pore-Size Distribution and Total Electrolyte Filling Degree on Molten Carbonate Fuel Cell Performance

“…In molten carbonate fuel cells ͑MCFCs͒ the loss of electrolyte during operation, due to corrosion and vaporization, is a major lifetime-limiting factor for nonpressurized systems. [1][2][3] To extend the lifetime it would be desirable to initially have as large an amount of electrolyte in the cell as possible. The drawback of this is high mass-transport resistances in the electrodes, leading to high overpotentials.…”