INVESTIGATION OF POROUS-ELECTRODES BY CURRENT INTERRUPTION - APPLICATION TO MOLTEN-CARBONATE FUEL-CELL CATHODES

A transient agglomerate model for simulation and analysis of experimen tal data, obtained by current interruption on porous molten carbonate fuel cell cathodes, is presented. The initial fast change of the poten tial after current interruption on a polarized NiO electrode is due to the closed-circuit potential distribution in the electrode. Conventio nal estimation of the iR corrected overvoltage by current interruption on porous electrodes, with finite electronic conductivity in the soli d phase and a finite ionic conductivity of the pore electrolyte, leads to an overcompensation of the external potential drop and an underest imation of the total steady-state overvoltage due to the internal curr ents passing in the electrode after interruption. The overcompensation of the external potential drop is directly proportional to the geomet ric current density and to the thickness of the electrode and inversel y proportional to the sum df the effective conductivities in the elect rode matrix and the pore electrolyte.