Electrochemical performance of Y 2O 3/NiO cathode in the molten Li 0.62/K 0.38 carbonates eutectics

Abstract

The preparation and subsequent oxidation of Ni cathodes modified by impregnation with yttria were evaluated by surface and bulk analysis. The electrochemical behavior of Y 2O 3/NiO cathodes was also evaluated in a molten 62 mol% Li 2CO 3 + 38 mol% K 2CO 3 eutectic at 650 °C by electrochemical impedance spectroscopy (EIS) as a function of yttria content and immersion time under the standard cathode gas condition (CO 2:O 2 = 67:33%). The stability tests of Y 2O 3/NiO cathodes showed that the yttria additive could dramatically reduce the solubility of NiO in the eutectic molten Li/K carbonates due to the preferential dissolution of yttria. The loss of yttria was confirmed by chemical analysis and X-ray diffraction (XRD). The Y 2O 3/NiO cathodes showed higher catalytic activity for oxygen reduction and lower dissolution of NiO than the pure NiO cathode. The cathode material with 1.0 wt.% of yttria showed the optimum behavior.