Configurational and electrical behavior of Ni-YSZ cermet with novel microstructure for solid oxide fuel cell anodes

A novel Ni-YSZ cermet anode for solid oxide fuel cell application has been developed in order to solve problems with our previous anode, which was prepared from a powder mixture of NiO and precalcined YSZ. In contrast to homogeneously sized YSZ in our previous anode, the new material has a YSZ frame made of coarse (average size of 27.0 mu m) and fine (average size of 0.6 mu m) powders to sustain the network of Ni and pore. Unlike the previous anode, no significant changes in shrinkage and microstructure of the new anodes were detected during sintering in air and upon transformation of NiO to Ni metal in a reducing atmosphere. The influence of the content of coarse YSZ powder was examined by fixing the Ni volume ratio at 40%. It has been found that with an increasing amount of coarse YSZ powder, the electrical conductivity increased by three orders of magnitude around 20 weight percent (w/o) coarse YSZ powder and also that the anode with an 80 w/o one was found to be the most stable during cell fabrication and cell operation. It is concluded that the consolidated framework made from two distinctly sized particles leads to a more stable YSZ frame and Ni network.