Fabrication of electrolyte-impregnated cathode by dry casting method for molten carbonate fuel cells

Abstract

A dry casting method for fabricating a porous Ni plate, which was used as the cathode for molten carbonate fuel cells, was proposed, and the basic characteristics of the as-prepared cathode were examined and compared with those of a conventional cathode fabricated by using the tape casting method. Through several investigations, we confirmed that the cathode fabricated by using the dry casting method has properties identical to those of the conventional cathode. Electrolyte-impregnated cathodes were also successfully fabricated by using the dry casting method. Several characteristics of the as-prepared electrolyte-impregnated cathodes including their electrical performance were investigated by using tests such as the single cell test. The cell performances of a single cell using a 25-wt% electrolyte-impregnated cathode and not the electrolyte-impregnated cathode were 0.867 V and 0.819 V at a current density of 150 mAcm⁻² and 650 °C, respectively. The single cell using a 25-wt% electrolyte-impregnated cathode was also operated stably for 2,000 h. The cell performance was enhanced, and the internal resistance and the charge transfer resistance were reduced after electrolyte impregnation in the cathode. Moreover, the increase in the surface area of the cathode and the further lithiation of the NiO cathode after the electrolyte impregnation in the cathode enhance the area of the three-phase boundary and the electrical conductivity, respectively. However, the cell performance of the single cell using the 35-wt% electrolyte-impregnated cathode was reduced, and the cell could not be operated for a long time because of the rapid increase in the N₂ crossover caused by the poor formation of a wet seal.