Study on wet-chemical coating fabrication process to develop metal-supported solid oxide fuel cell

Abstract

This dissertation addresses the metal-supported solid oxide fuel cell (SOFC) fabrication process. The main pur-pose of this dissertation is to develop a solution and coating process for depositing a dense electrolyte layer on a porous surface. The metal-supported SOFC fabricated by the solution coating process is also analyzed. The so-lution coating process for depositing a dense layer on a porous surface was experimentally investigated using PVP (polyvinyl pyrrolidine) and nanoparticles. PVP, which has a long coiled-chain structure, can increase solu-tion viscosity and relieve stress, while nanoparticles can control stress and reduce cracks. OCV (open circuit voltage) and SEM (scanning electron microscope) measurements confirmed that the solution-coated layer was dense throughout. Subsequently, studies on fabricating metal-supported SOFCs based on this new concept were conducted. To this end, a perforated Crofer22APU substrate, sol-gel coating and interconnect coating material were applied. Various experiments confirmed that the proposed metal-supported SOFCs were successfully de-veloped. EIS measurements of the fabricated single cell confirmed that a sufficiently dense electrolyte was fab-ricated, with a power density of 230 $mW/cm^2$. Then, to improve the performance of the metal-supported SOFCs, a wet infiltration technique was applied for the anode. Furthermore, the metal hole array was modified to im-prove the fuel supply considering the thermal stress. All the modified components were re-applied to fabricate a metal-supported SOFC. The newly developed fabrication process was successful using the modified compo-nents. The resulting performances were 315 $mW/cm^2$ at 700$\circ C$ and 150 $mW/cm^2$ at $600 \circ C$. Moreover, through measurements of long-term stability, a fully dense electrolyte was successfully fabricated, and the newly de-signed anode operated effectively. Finally, fabrication and evaluation of a large-area cell validated the newly developed fabrication process.