The current paper reports the details of challenges and progress in the joint project on development of metal supported solid oxide fuel cells and stacks by the teams of German Aerospace Center (DLR), ElringKlinger, Sulzer Metco and Plansee. An account of the materials is given followed by the advances in the processing techniques which include alternative plasma spraying and colloidal spraying. Improvement in the cell and stack design is then discussed followed by challenges faced during stack building and operations and solution implemented.

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The IDEAL-Cell concept is based on the junction between a PCFC anode/electrolyte section and a SOFC cathode/electrolyte section, through a mixed proton and oxide ion conducting porous ceramic membrane, operating in the temperature range 600-700°C. Recombination of ions takes place within the junction, or central membrane (CM), and water vapor is evacuated through open porosity. The first results on the fabrication of multilayered samples reproducing the IDEAL-Cell structure are reported here, together with electrochemical tests carried out on selected samples in order to evaluate the performances of the chosen materials and to demonstrate the feasibility of this innovative concept of fuel cell. Stable OCV and power generation were obtained in the multilayered structures. Anomalies in the I/V curves and impedance measurements under large perturbation could be considered as proofs of water formation inside the central membrane.

SUMMARYNanostructured coatings are fabricated for potential use as electrodes in solid oxide fuel cells (SOFC) by developing innovative plasma spraying methods. The nanostructured NiO1YSZ anodes are fabricated by three means: spraying of presynthesized agglomerates of nanoparticles, suspension dc plasma spraying and solution precursor dc plasma spraying. Cathode deposits of variety of chemical composition having nanostructure were fabricated by thermal plasma chemical vapor deposition (TP-CVD) using RF-plasma torch. The deposits of desired phase and microstructure were successfully produced. The nanostructured anode, fabricated by presynthesized agglomerates of nanoparticles, exhibited better gas permeability, comparable high temperature conductivity and 43% lower polarization in SOFC operation at 8001C compared with conventional anodes. Moreover, by controlling the electrode structure, the nanostructure of anode could be maintained for 1500 h of operation. Further improvement in the microstructure of anodes is in progress using dc plasma suspension and solution precursor spraying. Cathodes obtained from thermal plasma chemical vapor deposition (TPCVD) exhibited initially undesirable secondary phases, which were overcome by adjusting the chemical composition of the precursors. The deposit columnar structure had high open porosity and specific surface area.