Improvement of Lifetime of Molten Carbonate Fuel Cell. Effect of Fe and Co Additions on NiO Cathode Stability

Abstract

The most important cause of lifetime limitation of molten carbonate fuel cell (MCFC) is dissolution of the cathode NiO and precipitation of nickel in the electrolyte. Porous cathodes of NiO, 1-10 mol% Fe-doped NiO, and 5-25 mol% Co-doped NiO for the MCFC were prepared and used for the bench scale cells at temperature of 923 K. A initiation time of nickel short-circuiting for 10 mol% Fe-doped NiO was 2.3 times longer than that of NiO cathode in spite of almost the same nickel precipitation rate in the Li/K matrix. Moreover, Li/Na cell applied 10 mol% Fe added in NiO cathode with advanced matrix achieved about 9 times longer lifetime than Li/K cell applied NiO cathode with conventional matrix. On the other hand, the cell performance using 10 mol% Fe-doped NiO cathode is lower than that of conventional NiO cathode because of the unsuitable microstructure of the cathode. The optimization of microstructure is of importance to apply the Fe-doped NiO cathode to the MCFC.