A new candidate material for molten carbonate fuel cell cathodes

In this study the performance of a novel candidate material for the cathode of molten carbonate fuel cells (MCFCs), pre-oxidized nickel–niobium surface alloy, was investigated under various MCFC cathode conditions by the determination of the equilibrium solubility of nickel ions in the carbonate melt. The following conclusions can be drawn: (1) under a cathode atmosphere of p(CO2)/p(O2)=0.67/0.33 atm, the equilibrium solubility of nickel ions in (Li0.62, K0.38)2CO3 melt at 650°C is about 17×10−6 mol fraction for the nickel oxide electrode and 8×10−6 mol fraction for the pre-oxidized nickel–niobium alloy electrode; (2) under the selected MCFC cathode atmospheres with partial pressure of CO2 varying from 0.1 to 0.7 atm the dissolution reaction of NiO can be expressed as follows: NiO(s)+CO2(g)=Ni2+(l)+CO32−; and (3) temperature has less influence on the equilibrium solubility of the pre-oxidized nickel–niobium surface alloy electrode than on that of the NiO electrode. As far as the equilibrium solubility of nickel ions in the carbonate melt is concerned, the pre-oxidized nickel–niobium alloy can be considered as a candidate material for the cathode of MCFCs.