S. I. Vecherskii, M. A. Konopelko, N. N. Batalov, M. A. Zvezdkin, I. V. Zvezdkina.

ABSTRACT

Kinetics of oxygen reduction on “in situ” lithiated LaCoO3-d electrode in (Li0.62K0.38)2CO3 melt has been studied. It has been shown that under the experimental conditions the main electroactive species are superoxide ions and molecular oxygen, which correlates with studies on a gold electrode. However, the observed mechanism of the electrode reaction differed from the mechanisms proposed for the gold electrode. A number of mechanisms accounting the peculiarities of the oxide electrode have been proposed. Exchange current densities were found to be independent on the oxygen partial pressure and varied in the range 220–290 mA/cm2, depending on the experimental conditions and the supposed mechanism.

KEY WORDS

molten carbonate, fuel cell, perovskite, lanthanum cobaltite, oxygen reduction, electrocatalytic activity.

S. I. Vecherskii, M. A. Konopelko, B. D. Antonov, N. N. Batalov, M. A. Zvezdkin, I. V. Zvezdkina. 

ABSTRACT

Oxides LaCoO3-d + (z/2) Li2O (0 ≤ z ≤ 0.15) were synthesized and studied to elucidate variation of electrophysical properties of LaCoO3-d due to lithiation “in situ” in (Li0.62K0.38)2CO3 eutectic melt. It has been found that a perovskite-like solid solution (La1-хLix)(LiхСо1-х)O3-d, where х = z/(z + 2), forms as a result of doping by Li. The solid solution region does not exceed 2х = 0.072. At higher lithium content LiCoO2 appears along with the main perovskite-like phase. Single-phase samples exhibit a metallic type of conductivity and positive thermopower at the molten carbonate operating temperature 920 K. Electrical conductivity of Li-doped samples is 1.5 or less time smaller compared to LaCoO3-d, it varies in the range 3.2 × 104–3.8 × 104 S/m.

KEY WORDS

molten carbonate, fuel cell, perovskite, lanthanum cobaltite, electrical conductivity.