Fabrication of multi-layered structures for proton conducting ceramic cells

Protonic ceramic fuel cells offer a high potential to produce electrical energy in a very efficient way. The performance of such a device among others is highly dependent on the electrolyte material and its thickness. Therefore, multilayer structures are used to reduce the electrolyte thickness down to 10-20 mu m, supported by a much thicker porous anode. In this work sequential tape-casting is used to fabricate half-cells consisting of a BZCY electrolyte and a BZCY/NiO support which also serves as the anode layer. The starting powders are characterised as well as the thermal behaviour of the half-cells during heat treatment. Sintering experiments show that a temperature of T >= 1450 degrees C is needed to achieve the desired microstructure. After that a scale-up approach to a size of the half-cells of about 25 cm(2) is shown. The influence of the processing temperature on the microstructure is shown by detailed XRD and SEM studies. The formation of a BaY2NiO5 transient liquid phase during the heat treatment of the cells is clearly demonstrated. Finally, the proton conductivity of the tape-cast cells shows competitive values of sigma = 0.003 S cm(-1) at 600 degrees C with the advantage of an industrially proven and up-scalable manufacturing technique.