Porous nickel MCFC cathode coated by potentiostatically deposited cobalt oxide: II. Structural and morphological behavior in molten carbonate

Cobalt oxide was deposited on porous nickel by an electrodeposition technique as precursor of a novel MCFC cathode. The behavior of this cathode in molten (Li0.52Na0.48)2CO3 eutectics at 650 °C under an atmosphere of CO2:air (30:70) was studied before and after 50 h of exposure by different techniques. Before the exposure, the deposit of cobalt corresponded to a Co3O4 thin layer of. This crystalline structure was identified by XRD and Raman spectroscopy. After its exposure in the eutectic melt a loss of cobalt was observed by XRD, Raman spectroscopy, XPS, EDS and ICP-AES. The change in the Co3O4 structure into lithium–cobalt–nickel oxide (LiCo1−yNiyO2) was observed by Raman spectroscopy. The SEM micrographs for Co3O4-coated porous nickel showed different angular shapes with respect to porous Ni. The nickel solubility for the coated porous nickel, measured by ICP-AES, decreased with respect to uncoated nickel. The Co3O4-coated porous nickel cathode showed, after its immersion in the molten carbonate melt, a similar porosity but a higher pore size. LiCo1−yNiyO2-coated NiO offers interesting features which combine the properties of nickel, lithium and cobalt in molten carbonate. This could be a promising novel MCFC cathode material.