FACTORS AFFECTING THE DISSOLUTION AND REDUCTION OF OXYGEN IN MOLTEN-CARBONATE ELECTROLYTES .2. EFFECT OF SRCO3, BACO3 AND SNO2 ADDITIVES

The effect of minority SrCO3, BaCO3, and SnO2 additions to various alk ali carbonate electrolytes has been investigated for both oxygen reduc tion kinetics and also oxide ion activity. Although alkaline earth met al additives were found to assimilate into the melt with relative ease , metal oxides of higher valency were found to be fairly insoluble. In general, addition of earth metal carbonates to the electrolyte provid es a means of increasing the effective oxygen solubility. The nature o f the improvement appears to vary with the additive used, the amount a dded, and the original electrolyte composition. In all cases there was a significant increase in background current. In view of surface ener gy considerations, this is most probably due to increased carbon dioxi de diffusion and meniscus effects. In addition to the increase in oxyg en dissolution, there appears to be a concurrent increase in the oxide ion activity.