Solid Oxide Fuel Cell Electrolytes Prepared by a Combination of Suspension Plasma Spray and Very Low Pressure Plasma Spray

Solid oxide fuel cells (SOFCs) are a promising piece of the solution to rising world energy problems because they provide a direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. While conventional air plasma spray is efficient at deposition on complex surfaces, such as those for non-planar SOFC designs, it produces porous, thick (>50 µm) coatings un-suited for electrolyte performance. A method for forming dense, thin electrolytes of ideal composition is possible by using suspension plasma spray at very low pressures (< ~800 Pa). In the work reported, feedstocks consisting of ~0.5 µm diameter 8 mol% Y₂O₃-ZrO₂ (YSZ) powders have been prepared in suspension with 0-8 mol% of scandium-nitrate dopants. These coatings were prepared in a chamber held at pressures from 300-800 Pa on NiO-YSZ anodes at Sandia National Laboratories’ Thermal Spray Research Laboratory. The resultant electrolytes were 2-10 microns thick. The role of process parameters on the microstructure and electrical performance (I-V behavior) of the electrolytes, when used in a fuel cell, will be reported.