The Development of LiFeO2—LiCoO2—NiO Cathodes for Molten Carbonate Fuel Cells.

The phase relationships in the LiFeO{sub 2}-LiCoO{sub 2}-NiO ternary system were determined and used to find compositions that would reduce the resistivity of LiFeO{sub 2}-containing cathodes to levels low enough for molten carbonate fuel cells. There was no solubility limit in the NiO-LiFeO{sub 2} binary system; a continuous solution was formed. Two regions of homogeneity were found in the LiFeO{sub 2}-LiCoO{sub 2} binary, 0 to 13 and 87 to 100 mol % LiCoO{sub 2}. Similarly, two regions of homogeneity were found in the LiCoO{sub 2}-NiO binary, 0 to 18 and 94 to 100 mol % LiCoO{sub 2}. The resistivities of these materials indicate that addition of Ni and Co to the LiFeO{sub 2} lattice decreases the resistivity from about 300 {Omega} cm to about 1 to 10 {Omega} cm at 650 C. Using both Ni and Co additives together reduces the resistivity of LiFeO{sub 2} and its sensitivity to CO{sub 2} partial pressure. Cell tests indicate that solid solutions LiFeO{sub 2}-LiCoO{sub 2}-NiO system posses electrocatalytic activity. The cell displayed a potential of 0.79 V at 160 mA/cm{sup 2}. The data indicate that LiFeO{sub 2}-LiCoO{sub 2}-NiO cathodes hold promise for fuel-cell cathodes.