A stabilized NiO cathode prepared by sol-impregnation of LiCoO2 precursors for molten carbonate fuel cells

Abstract

Layers of LiCoO2 were formed on the internal surface of a porous NiO cathode to reduce the rate of NiO dissolution into the molten carbonate. A sol-impregnation technique assisted by acrylic acid (AA) was used to deposit gel precursors of LiCoO2 on the pore surface of the Ni plate. Thermal treatment of the gel-coated cathode above 400 degreesC produced LiCoO2 layers on the porous cathode. A number of bench-scale single cells were fabricated with LiCoO2-coated cathodes and the cell performance was examined at atmospheric pressure for 1000 h. With the increase in the LiCoO2 content in the cathode, the initial cell voltage decreased, but the cell performance gradually improved during the cell test. It was found from symmetric cathode cell test that the cathode was initially flooded with electrolyte, but redistribution of the electrolyte took place during the test and cell performance became comparable to that of a conventional NiO cathode. The amount of Ni precipitated in the matrix during the cell operation for 1000 h was significantly reduced by the LiCoO2 coating. For instance, coating 5 mol% of LiCoO2 in the cathode led to a 56% reduction of Ni precipitation in the matrix. The results obtained in this study strongly suggest that LiCoO2 layers formed on the internal surface of the porous NiO cathode effectively suppress the rate of NiO dissolution for 1000 h. (C) 2002 Elsevier Science B.V. All rights reserved.