Micro-tubular solid oxide fuel cells (SOFC) systems have many desirable characteristics compared to their planar counter-parts, however there are many obstacles and difficulties that must be met to achieve a successful and economically viable manufacturing process and stack design. Anode supported tubes provide an excellent platform for individual cells. They allow for a thin electrolyte layer, which helps to minimize polarization losses, to be applied to the outside of the tube, thus avoiding the difficulty of coating the inside of an electrolyte or cathode supported tubes, or the stack design problem of having a fuel chamber if the anode is on the outside of the tube.

This paper describes the fabrication of a traditional (Ni-YSZ) anode tube via extrusion of a plastic mass through a die of the required dimensions. The anode tubes were dried before firing, and tests performed on the tubes to determine the effects of pre-firing temperature on porosity. The porous tubes had a vacuum applied to the inside while being submerged in aqueous electrolyte slurry. Various parameters were examined, including vacuum pressure, submergence time, and drying conditions, and studied using light microscopy. Cathode coatings (based on both doped lanthanum manganite and doped lanthanum cobaltite) were applied using a brush painting technique, and optimized as a function of paint consistency, drying conditions, and firing temperatures

The finished tubes were then stacked in an array to provide the specific current/voltage requirements, using a brazing technique. This paper will describe the output characteristics (thermal, power, voltage, and longevity) of a single cell, and a small stack (of 100 We designed power output) running off hydrogen and methane.