Optimization of the electrolyte composition in a (Li0.52Na0.48)2−2xAExCO3 (AE = Ca and Ba) molten carbonate fuel cell

We report that the addition of the alkaline-earth carbonates CaCO3, SrCO3 and BaCO3, to an alkali carbonate mixture effectively reduced the solubility of nickel oxide in a molten carbonate. In addition, we discuss the molten carbonate fuel cell (MCFC) performance with a ternary system of (Li0.52Na0.48)2−2xAExCO3 (AE = Ca, Sr and Ba). Although the solubility of nickel oxide in the molten carbonate was reduced with an increase in the amount of additives, large amount of additives bring a low cell performance. We have made progress in the optimization of the carbonate composition through investigations as to durability by small-sized cell testing under a pressurized condition. The addition of SrCO3 was deemed inadequate by the failure of cell voltage within a 1000-h operating period. From the single cell operation results of periods up to 5000 h, we concluded that the addition of 9 mol% CaCO3 and 9 mol% BaCO3 to 52 mol% Li2CO3–Na2CO3 preserved the cell performance. This electrolyte composition is expected to yield an efficiently performing and durable MCFC.