Development of Ni-YSZ cermet anode for solid oxide fuel cells by electroless Ni coating

Nickel-Yttria-stabilized zirconia (Ni-YSZ) cermet (ceramic-metal composite) anodes have been prepared from a simple electroless Ni bath without hypophosphite. Ni-YSZ powder having varying amounts of Ni has been prepared. The effect of two different reducing agents has been evaluated with respect to stability of the bath. Hydrazine can be effectively used as a reducing agent up to 30 vol.% Ni. However beyond 30% Ni, the hydrazine bath loses its stability. Formaldehyde is found to be a very effective reducing agent for higher Ni concentration. The Ni-YSZ powder obtained is characterized by SEM and XRD. When the powder is oxidized for calculating actual amount of Ni deposited, it turns to complete green due to the formation of NiO. The XRD results also show distinct peaks of NiO. The powder is pressed and sintered in air and reduced in hydrogen atmosphere to convert NiO back to Ni. The sintered microstructure shows a well-defined network of Ni around YSZ particles and the fracture surface shows porosity. These features indicate the effectiveness of the technique in producing the essential microstructural elements necessary for effective functioning of the anode. © 2009 FSCT and OCCA.