Materials, interfaces and production techniques for planar solid oxide fuel cells
Abstract Solid oxide fuel cells based on an yttria-doped zirconia electrolyte were developed. Electrodes and interconnectors were made from electronic conductors such as Ca-doped LaMnO3 (cathode), a Ni-cermet (anode) and doped LaCrO3 (interconnect). After having optimized the electrical, mechanical and thermo-mechanical properties in the past, the emphasis of this work was orientated towards the interfaces between the electrolyte and the electrodes. By use of interfaces out of mixed conducting materials with small grain size, the best electrochemical performance was achieved. For creating the interfaces, a thin interlayer was directly applied on the electrolyte as a first step in the electrode production process. Single cells and cell stacks were manufactured by tape casting of the electrolyte, screen printing of the electrodes and joining the cells by glass sealing. The area specific resistance at 1000 °C was about 0.8 Ω cm2, about one third being caused by ohmic losses and two thirds by polarization. Lifetimes of about 2 years for single cells and of 0.7 years for ten-cell stacks were achieved.