ANALYSIS OF PERFORMANCE OF MOLTEN-CARBONA TE FUEL-CELL .3. THE EFFECTOF NIO CATHODE DISSOLUTION ON THE CELL LIFE

The NiO cathode used for a present MCFC dissolves into the matrix as N i2+ ion. Ni2+ ion is reduced to Ni in the matrix and Ni builds the bri dge between anode and cathode. The bridge works as short circuit and d egrades cell performance and life. The several single cells have been used for the evaluation of the cell performance and life under the sho rt circuit. The following results have been obtained: (1) It is possib le to predict the cell performance and life under the short circuit fr om short-term accelerated tests in high partial pressure of cathode CO 2. Because the amount of Ni deposited in the matrix has been found to be proportional to the cathode CO2 partial pressure. (2) It is also po ssible to detect the short circuit by monitoring the CO2 concentration in the anode exhaust gas. (3) The time-to-short is proportional to th e inverse of the cathode CO2 partial pressure and to the second power of the matrix thickness. Based on these results, a degradation model o f cell performance has been developed and can be used for an estimatio n of the initial performance and the cell life.