Electrochemical deposition of doped ceria for the performance improvement of thin-film solid oxide fuel cells

Abstract

Solid oxide fuel cells are next-generation energy conversion devices with high efficiency. Thin-film solid oxide fuel cell (TF-SOFCs) with reduced electrolyte thickness was developed as part of an attempt to reduce high operating temperature, which is the cause of performance degradation. At low operating temperatures, cathodes have the greatest effect on the performance of a single cell. Electronic conductivity, process compatibility, and thermal/chemical stability, as well as electrode performance, are important indicators for the selection of cathode materials. Although nanoporous silver satisfies the criteria, the thermal instability due to agglomeration is a major disadvantage. To overcome this issue, several studies have been reported to improve stability with oxide coating methods such as atomic layer deposition, sputtering, and infiltration. However, they are not suitable for the actual process because of the complexity of the process or the need for high-temperature heat treatment. However, coating doped ceria with cathodic electrochemical deposition (CELD) technology has been recently reported to improve the performance and stability of platinum-based cathodes easily and quickly over the conventional method, which can also be applied to silver electrodes. This thesis aims to demonstrate for the first time that the CELD is applicable for the improvement of TF-SOFCs. Doped-ceria was coated onto the nanoporous silver film by CELD and analyzed by electron microscopy, mass spectrometry, and X-ray diffraction. Cathode characterization platform was organized with electrolyte-supported type single-cells and various electrochemical characterizations suggests CELD as a powerful strategy to enhance the performance and stability of TF-SOFCs.