Controlled-Pore-Size Composite Nickel Oxide Structures for Carbonate Fuel Cell Cathodes

The performance of a molten carbonate fuel cell (MCFC) is significantly eroded when fuel and oxidant gases are allowed to combine chemically as occurs with a loss of gas impermeability by the cell's electrolyte structure. This performance decline is eradicated when the cell's electrodes possess pore size distributions small enough to absorb sufficient electrolyte to act as a secondary gas barrier. Described here is a process for preparing composite MCFC NiO cathodes where the median pore size of the gas barrier region is varied from 3.2 to 0.4 μm by adjusting the starting powder's Ni/NiO ratio. When filled with liquid Li₂CO₃-38 mol% K₂CO₃ at 923 K, these structures possess a gas pressure resistance of between 2.3 × 10⁵ and 13.6 × 10⁵ Pa, respectively. The incorporation of these composite cathodes in a MCFC can prevent the penetration of the oxidant gas into the fuel cell's interior.