Dissolution behavior of Co-coated NiO cathode in molten (Li0.62K0.38)2CO3 eutectics

Abstract

The dissolution behavior of the NiO–CoO electrodes in molten (Li 0.62 K 0.38 ) 2 CO 3 eutectics as a function of Co content was investigated under the standard cathodic gas composition at 650 °C. In order to prepare NiO–CoO electrodes, Co was deposited on the porous Ni electrode using galvanostatic pulse plating technique followed by the oxidation process. Compared to the pure NiO electrode, NiO–CoO electrodes showed low Ni solubility in molten (Li 0.62 K 0.38 ) 2 CO 3 eutectics. Solubility of NiO–CoO electrodes depended on the partial pressure of carbon dioxide ( P CO 2 ) and the Ni solubility increased with P CO 2 . On the other hand, the Ni solubility was not affected by the partial pressure of oxygen ( P O 2 ). The XRD analysis after the dissolution experiment, showed that the Ni solubility decreased with increase of the amount of lithium incorporated in the electrodes and that the lithium incorporation was promoted by the formation of NiO–CoO solid solution. The results obtained in the present study suggested that NiO–CoO solid solution could effectively suppress the NiO dissolution in the molten (Li 0.62 K 0.38 ) 2 CO 3 eutectics.