Fabrication of Dense Electrolyte for Metal-Supported Solid Oxide Fuel Cells by Plasma Spray Method

Metal-supported SOFCs (MS-SOFCs) have attracted attention because of their potential for low cost and high mechanical robustness. However, the conventional cell fabrication process is not easily applied to MS-SOFCs. The difficulty of MS-SOFC fabrication is especially to form a dense electrolyte without oxidation and diffusion of the metal support. We’ve tried to use a plasma spray method to prepare the metal supported cells. Then, apparently dense electrolyte layer could be fabricated using doped lanthanum gallate instead of yttria stabilized zirconia. In this paper, electrochemical performance and gas tightness of the cells were evaluated to consider the applicability of plasma spray for MS-SOFC fabrication. A prepared MS-SOFC consists of porous metal substrate (SUS430), NiO-YSZ anode, Sr-, Mg-doped lanthanum gallate (LSGM9182), and conventional cathode (LSCF6428). The cell components, except for the porous substrate, were deposited by atmospheric pressure plasma spray (APS). Gas tightness of the cell was confirmed by open circuit voltage (OCV) measurement. Cell performance was evaluated by current-voltage measurement and impedance measurement. Post-analysis of the cell was conducted by SEM/EDS. The measured OCV was confirmed to be equivalent to theoretical value in humidified hydrogen at 973 K. It means the fully dense electrolyte layer could be prepared by plasma spray. Current density of I-V measurement was 0.6 Acm-2 at 0.5 V at 973 K. The impedance results showed larger over potential of anode reaction. This might be caused by anode electrochemical reaction and gas diffusion through anode and substrate layer. Further development of plasma spray anode is necessary for practical application; however, this study confirmed the possibility of the plasma spray method to fabricate the dense electrolyte for MS-SOFCs. This research was financially supported by NEDO.