CELL PERFORMANCE OF MOLTEN-CARBONATE FUEL-CELL WITH ALKALI AND ALKALINE-EARTH CARBONATE MIXTURES

Molten-carbonate fuel cells with two types of alkali carbonate mixture as the electrolyte have been operated. The resulting cell performances have been compared in order to optimize the composition of each carbonate mixture. One electrolyte type is a mixture of the high lithium eutectic ((Li0.62K0.38)2CO3) and an alkaline-earth carbonate, while the other is a mixture of the lithium-sodium eutectic ((Li0.52Na0.48)2CO3) and an alkaline-earth carbonate. Additions of CaCO3, SrCO3 and BaCO3 have been used. A small amount of each alkaline-earth carbonate to both eutectics does not influence the cell performance. On the other hand, larger amounts reduce the cell performance. The required content of each additive to provide optimum cell performance depends on both the additive itself and the host eutectic. The temperature dependence of cell performance in the presence of the different additives has also been investigated. There is little difference between the behaviour of ((Li0.62K0.38K0.38)2-Ca)CO3, ((Li0.62K0.38)2-Ba)CO3 and ((Li0.52Na0.48)2-Ca)CO3. By contrast, high temperature dependence was found for ((Li0.62K0.38)2-Sr)CO3, ((Li0.52Na0.48)2-Sr)CO3 and ((Li0.52Na0.48)2-Ba)CO3.