Effects of water on cathodic performance of Ba0.6La0.4CoO3 on the cell using LaGaO3-BASED oxide for electrolyte

Effects of water addition to oxidant on the cathodic overpotential of La-doped BaCoO 3 electrode were investigated. It was found that the overpotential of La-doped BaCoO 3 decreased by addition of H 2 O to oxygen. In particular, the decrease in overpotential by addition of H 2 O was significant with decreasing operating temperature of the cell. Therefore, it became clear that the maximum power density increased by addition of H 2 O to oxidant. The improved cathodic activity by addition of H 2 O was further studied by using 18 O tracer exchange measurement. Although the diffusion coefficient was independent of the coexisting water, the surface exchange coefficient increased greatly by addition of water. 18 O- 16 O isotopic exchange reaction under coexisting H 2 16 O demonstrated that the surface oxygen exchange reaction through H 2 O is very fast and the coexisting water catalytically accelerates the dissociation reaction of gaseous oxygen molecule into oxide ion. The positive effects of humidified oxidant were stable over 50 hours of testing.