Design and fabrication of a 100 W anode supported micro-tubular SOFC stack

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 supporting anode tubes made of nickel and yttria stabilized zirconia (Ni-YSZ), coated with a thin YSZ electrolyte and a thin coat of lanthanum strontium manganite/cobaltite (LSM) cathode. The finished tubes were then stacked in an array to provide the specific current/voltage requirements, using a brazing technique. A description of the output characteristics of the single cell, and the characteristics and main issues of a small stack (of 100 We designed power output) are also given.