Solubility of cobalt oxide in molten carbonate

The molten carbonate fuel cell (MCFC) is expected to be one of the most promising power generation systems for the coming century owing to its high efficiency, reduced quantity of air pollution, and flexibility to a variety of fuels. In this system, durability is the key point for practical operation. The stability of the cathode material under cathodic conditions and corrosion resistance of the metallic components in the presence of molten carbonate are considered to be very important factors for commercialization. The solubility of Co oxide in (Li{sub 0.62}K{sub 0.38}){sub 2}CO{sub 3} melt has been studied in Co{sub 2}-O{sub 2} atmospheres at 873--1,073 K. The stable phase of Co oxide in the melt was LiCoO{sub 2} under O{sub 2} and CO{sub 2}. At high CO{sub 2} pressure (P{sub CO{sub 2}}>0.1 atm) the acid dissolution was observed and the solubility of Co oxide was proportional to P{sub CO{sub 2}}. Although the solubility was lower than that for NiO, the pressure dependence was larger. At low CO{sub 2} pressure (P{sub CO{sub 2}}