Characterization of the electrode and electrolyte interfaces of LSGM-based SOFCs

LSGM is known to have a critical limit in terms of its application due to its chemical reactivity with other unit cell components. In particular, the formation of a highly resistive La-Sr-Ga-O phase at the interface of the anode and electrolyte poses a major obstacle toward the application of LSGM-based SOFCs. In this study, we investigated the interfacial reactions in LSGM-based SOFCs under various fabrication conditions in order to identify a means of avoiding or diminishing undesirable interfacial reactions. The electrical properties and phase composition of all reaction products were analyzed with the DC 4-point probes technique and X-ray diffraction. Microstructural evolution due to the chemical reactions between unit cell components was characterized with Environmental Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy. According to the analysis of the interfacial reaction, a serious reaction zone exists, critically increasing the internal ohmic resistance of the cells. Moreover, this interfacial reaction decreases the OCV (open cell voltage) and consequently deteriorates the unit cell performance. Possible approaches to solving this reaction problem are reducing the heat-treatment temperature or introducing an effective buffering layer to prohibit interfacial reaction.