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Research paper : Challenge for the development of micro SOFC manufacturing technology (Y. Fujishiro et al.)−48−Synthesiology - English edition Vol.4 No.1 (2011) prototype manufacture, evaluation, and analysis was set forth toward the mass production of high-performance fuel cell materials that used to be considered unsuitable for the forming technology. Moreover, since the investigation of the structural control that determined the optimal condition was done concurrently with prototype evaluation, the new high-performance micro SOFC and the highly integrated compact module manufacturing were developed in a short time.3 Issues in manufacturing the micro SOFC for the high-efficiency compact energy module ~ Valley of death in product realization and the solutionFor the micro SOFC and integrated module manufacturing technology that was not available before, it was necessary to develop the ceramic manufacturing process that could be mass produced industrially, the electrochemical design of the module of highly integrated micro SOFC, and the technologies for increasing performance. As a new manufacturing process technology under the concept of fusion of function and structure, we shall explain the manufacturing design in the R&D model of Fig. 3 and the development of new structure control process technology.i) Highly integrated micro SOFC manufacturing and design technologyTo increase the performance of the SOFC module, it was necessary to increase the electrode surface area per unit module volume, raise the degree of cell integration, and improve the mechanical strength. For the structure that fulfilled such requirements, it was advantageous to achieve high integration by both the bottom-up manufacturing where the unit cell members were combined and highly integrated, and the top-down manufacturing where the cell structure was built in later using the regularly arrayed micro-channel. To increase the performance of micro SOFC which made use of the conventional manufacturing technology of tubular SOFC, the bottom-up structure of development of the high integration of tubular SOFC was effective. On the other hand, to reduce the cost of module manufacturing and to achieve advanced cell integration structure, it was necessary to develop a new technology where the module with equivalent performance obtained in the bottom-up manufacturing was made by top-down manufacturing. In this R&D, considering the high performance and cost reduction, the R&Ds were conducted for the two types of module manufacturing technology including the tube integration module and the honeycomb micro SOFC.To bring out the advantages of high efficiency and high power density in SOFC power generation, we needed to consider the technologies to improve the reactive surface area of the electrode to enable effective progression of the electrochemical reaction of the supplied fuel, as well as the module structure that allowed the integration of current and gas flow. Ultimately, it was mandatory to select the manufacturing process technology in a form that could be mass-produced, as several cells were needed for high integration. For the reduction of cell resistance that enabled high performance at low temperature range, the support structures of the Anode, Cathode, and the electrolyte were crucial, as shown in Fig. 4. This was because the resistance became minimum in the cermet anode that was partially metalized by reduction. The tubular integrated body with high symmetry of stress distribution was superior to the planar structure as a unit structure that achieved the mechanical strength and also improved the relative surface area of the porous electrode by increasing the degree of integration.As researches for similar microtube SOFC, there have been studies on rapid startup using the YSZ electrolyte supported SOFC at 2~5 mm level with high thermomechanical strength[8][9]. However, there were very few developments for the manufacturing technology for high performance such as achievements at low temperature range of 650 °C or less or the development of small integrated modules. Our challenge was to manufacture high-performance SOFC and integrated modules unseen before, and therefore, we investigated the manufacturing technology of the integrated modules composed of anode supported micro SOFC. Moreover, although there were only a small number of studies since the mechanical strength was low and forming was difficult, we developed the manufacturing process using ceria electrolytes with high oxide ion conductivity at low temperature.As the technologies for manufacturing and design of the microtube SOFC and integrated module with fuel gas pores Fig. 4 Structure of various fuel cellsFig. 5 Design model and the results of current collection loss calculation for the integration of the micro-tubular SOFC design technologya)Anode supportedc)Electrolyte supportedb)Cathode supportedCathodeElectrolyteAnode123451E-30.010.11bothend3%losst=0.4mmt:anodethickness1.6mmtube550oC0.5W/cm2operationTubelength-L,cm1end3 % Single-end current collection550 ℃0.5 Wcm2Thickness of fuel electrode 0.4mm2.0 mmΦ Current collection loss (%)100101 0.112345Length of tube cell L (cm)Double-end current collection modelCurrent collection areaΔx LSingle-end current collection modelDouble-end current collection

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