The Effects of Nickel Oxide Cathode Dissolution on Molten Carbonate Fuel Cell Life

Abstract

The dissolution f lithiated nickel oxide cathodes results in a transport of nickel into the fuel cell matrix and can result in an electronic short circuit between the electrodes. A theoretical nalysis was developed for this process, accounting for the dissolution, diffusion, transference, and convection of nickel. Experimental data obtained on post-test nickel content in matrices and shorting time w re found to be correlated by this theory, except for a current density effect hat was un-derpredicted. This poor prediction of the current density effect is postulated tobe caused by cation segregation during cell operation. These results enable the estimation f matrix nickel content and shorting time as a function of cell design and operating conditions. Lithiated nickel oxide cathodes that are presently used in molten carbonate fuel cells have been found to dissolve in the electrolyte and result in the deposition of metallic nickel in the cell matrix (1). This nickel deposition can re-sult in the formation of an electronically conducting bridge between the electrodes and degrade cell perform-ance. Because this dissolution of nickel oxide from the