Characterization of Anode/Electrolyte Interface for Advanced Anode Structures

A multilayer structure was used for the Ni/8YSZ cermet anode. The electrochemically active NiO/8YSZ anode layer was screen printed onto a 8YSZ electrolyte green tape and cofired at 1350 °C. Mechanical stresses during cofiring due to shrinkage mismatch of anode and electrolyte were avoided by changing the geometry of the anode layer from a continuous layer to a large number of small sized individual areas. A hexagonal pattern similar to honey-combs was used as it yields the lowest stresses for a given area coverage. The second layer which adjoins to the fuel gas channels and which acts as current collector and gas distributer was later on screen printed on top of the first layer and sintered together with the cathode. Single cells with this type of multilayer anode were electrochemically characterized under realistic operation conditions. The performance and reduction/oxidation stability of this type of anode was investigated. The electrochemically active layer showed only small degradation during redox cycling and long term operation at high fuel utilization. In contradiction to single layer anodes Nickel agglomeration was not observed in the functional layer.