Characterization of Li-Co-Ni Mixed Metal Oxide as Alternative Cathode Material for Molten Carbonate Fuel Cells

Abstract

Li-Co-Ni mixed metal oxide is expected to be as stable in molten carbonates as LiCoO₂ and attain conductivity as good as lithiated NiO. The present study examined the behavior of Li-Co-Ni mixed metal oxide in molten carbonates and its characterization as an alternative cathode material for molten carbonate fuel cells. It was found that phase separation occurred if the partial pressure of carbon dioxide was high. In this case, formation of NiO is dominant. The concentrations of Ni and Co in molten carbonates approach to respective solubilities of NiO and LiCoO₂ as the decomposition reaction progresses. Also this oxide has no substantial solubility suppression effect. The conductivity of this material is affected by phase separation, therefore care must be directed to the partial pressure of carbon dioxide. As a result of a single cell test for 10000 hours using mixed metal oxide as cathode, it was recognized that Co deposited on the anode surface, though its effect of cell performance was left uncertain.