Insight into cathode microstructure effect on the performance of molten carbonate fuel cell

Abstract

This paper deals with the effect of pore size distribution within the cathode on the performance of molten carbonate fuel cells. The X-ray tomography images of four materials are used to create 3D geometrical models of the cathodes pore structure so that the modeling takes into account the actual variations in pore size of the real materials. The simulation includes the cathode infiltration process by the liquid electrolyte which is governed by capillary action. This allows one to quantify the triple phase boundary (cathode/electrolyte/gas) density which is commonly viewed as providing active sites for cathodic reactions. It has been found that this parameter does not correlate well with the maximum power density of the cell. On the other hand, increasing the specific surface area of the gas/electrolyte interface correlates well with higher cell performance. Following our in-depth modeling and analysis we postulate that the dominant mechanism, when larger pores are introduced by the addition of porogens, is the creation of continuous pathways for the transport of gases to come into contact with the cathode surface through the thin film of electrolyte.