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The long-term stability of SOFC stacks is a critical hurdle to their commercial success. To maintain low stack and system costs, metallic interconnect materials are required; to achieve long life, protective coatings must stabilize metal interconnect performance. Further, these coatings must exhibit sufficient bulk conductivity to achieve low stack area specific resistance. To exploit the cost advantages offered by metallic interconnects, coating approaches must be size-scalable and allow high volume throughput at low capital cost. NexTech has systematically developed cost-effective approaches to synthesizing and depositing oxide coatings through value-conscious materials processing and deposition processes. Recently, manganese cobalt spinel synthesis and deposition has been demonstrated using production process designed to allow high throughput production.

A critical component in spacecraft life support loop closure is the removal of carbon dioxide (CO2, produced by the crew) from the cabin atmosphere and chemical reduction of this CO2 to recover the oxygen. In 2015, we initiated development of an oxygen recovery system for life support applications consisting of a solid oxide co-electrolyzer (SOCE) and a carbon formation reactor (CFR). The SOCE electrolyzes a combined stream of carbon dioxide (CO2) and water (H2O) gas mixtures to produce synthesis gas (e.g., CO and H2 gas) and pure dry oxygen as separate products. This SOCE is being developed from a NASA GRC solid oxide fuel cell and stack design originally developed for aeronautics longduration power applications. The CFR, being developed by pHMatter LLC, takes the CO and H2 output from the SOCE, and converts it primarily to solid carbon (C(s)) and H2O and CO2. Although the solid carbon accumulates in the CFR, the innovative design allows easy removal of the carbon product, requiring minimal crew member (CM) time and low resupply mass (1.0 kg/year/CM) for replacement of the solid carbon catalyst, a significant improvement over previous Bosch reactor approaches. In this work, we will provide a status of our Phase I efforts in the development and testing of both the SOCE and CFR prototype units, along with an initial assessment of the combined SOCE-CFR system, including a mass and power projections, along with an estimate of the oxygen recovery rate.

As solid oxide fuel cell technology enters product commercialization, low cost manufacturing and long-term stability of SOFC is critical to the success in the industry. Materials that can be produced in a scalable manner and simply integrated into stack manufacturing are important to achieve these goals. In this paper, materials evaluations of low temperature cathodes, interconnect coatings and contact paste development are reviewed.

This report describes results obtained by NexTech Materials, Ltd. in a project funded by DOE under the auspices of the Solid-State Energy Conversion Alliance (SECA). The project focused on development of YSZ electrolyte powder synthesis technology that could be "tailored" to the process-specific needs of different solid oxide fuel cell (SOFC) designs being developed by SECA's industry teams. The work in the project involved bench-scale processing work aimed at establishing a homogeneous precipitation process for producing YSZ electrolyte powder, scaleup of the process to 20-kilogram batch sizes, and evaluation of the YSZ powder products produced by the process. The developed process involved the steps of: (a) preparation of a an aqueous hydrous oxide slurry via coprecipitation; (b) washing of residual salts from the precipitated hydroxide slurry followed by drying; (c) calcination of the dried powder to crystallize the YSZ powder and achieve desired surface area; and (d) milling of the calcined powder to targeted particle size. YSZ powders thus prepared were subjected to a comprehensive set of characterization and performance tests, including particle size distribution and surface area analyses, sintering performance studies, and ionic conductivity measurements. A number of different YSZ powder formulations were established, all of which had desirable performance attributes relative to commercially available YSZ powders. Powder characterization and performance metrics that were established at the onset of the project were met or exceeded. A manufacturing cost analysis was performed, and a manufactured cost of $27/kg was estimated based on this analysis. The analysis also allowed an identification of process refinements that would lead to even lower cost. Continuous Process for Low-Cost, High-Quality YSZ PowderPhase II Final Report DOE Contract Number: DE-FC26-02NT41575 March 31, 2006 -3 - Executive SummaryIn this SECA Core Technology project, NexTech Materials developed a powder synthesis process for production of yttrium stabilized zirconia (YSZ) electrolyte powder. The objective of the project was to demonstrate -at sufficient scale -a low-cost and flexible, homogeneous precipitation process that reproducibly provides high quality YSZ electrolyte precursor powders for fabrication of solid oxide fuel cells.One of the current barriers to reducing the manufacturing cost of SOFCs is the high cost of some of the critical raw materials. YSZ is perhaps the most important, since it is used for the electrolyte layer and as a component in the anode and cathode layers. The availability of a lowcost, highly reliable and reproducible supply of engineered raw materials is necessary to assure successful commercialization of SOFC technology. Not only is low cost a requirement for the YSZ raw material, but also the ability to tailor the characteristics of electrolyte powders to those required for SOFCs will provide additional performance and cost benefits.Work on this project involved bench-scale powder synthes...