Group IVA Oxide Surface Modification of LSCF Cathode Powders by Atomic Layer Deposition

(La0.6Sr0.4)(0.95)Co0.2Fe0.8O3-delta (LSCF) powder has been modified by atomic layer deposition (ALD) with Group IVA based oxides, including zirconia, hafnia, and cobalt doped compositions. Amide zirconium and hafnium and amidinate cobalt precursors were used in an ALD process to treat 0.3 mu m nominal diameter LSCF powder at 240 degrees C using water as a co-reactant. The effect of the number of ALD cycles and level of Co additions have been examined up to 15% Co. The morphology and physical properties of sintered samples were similar to untreated powders with a modest shift to lower porosity and pore volume, but well within the desired range of microstructural properties. Depending on the recipe, initial polarization of cathodes in symmetrical electrochemical cells varied slightly compared to uncoated powders. Degradation of cathodes made from treated powders was improved compared to cathodes made from untreated powders.