The development of LiFeO2-LiCoO2-NiO cathodes for molten carbonate fuel cells

The phase relationship in the LiFeO2-LiCoO2-NiO ternary system were determi ned and used to find compositions that would reduce the resistivity of LiFe O2-containing cathodes to levels low enough for molten carbonate fuel cells . There was no solubility limit in the NiO-LiFeO2 binary system; a continuo us solution was formed, Two regions of homogeneity were found in the LiFeO2 -LiCoO2 binary, 0 to 13 and 87 to 100 mol % LiCoO2. Similarly, two regions of homogeneity were found in the LiCoO2-NiO binary, 0 to 18 and 94 to 100 m ol % LiCoO2. The resistivities of these materials indicate that addition of Ni and Co to the LiFeO2 lattice decreases the resitivity from about 300 Om ega cm to about 1 to 10 Omega cm at 650 degrees C, Using both Ni and Co add itives together reduces the resistivity of LiFeO2 and its sensitivity to CO 2 partial pressure. Cell tests indicate that solid solutions LiFeO2-LiCoO2- NiO system posses electrocatalytic activity. The cell displayed a potential of 0.79 V at 160 mA/cm(2). The data indicate that LiFeO2-LiCoO2-NiO cathod es hold promise for Fuel-cell cathodes. (C) 1999 The Electrochemical Societ y. S0013-4651(98)06-071-6. All rights reserved.