The reaction and cathodic overpotential of LaGaO3-based solid oxide fuel cell

Although La1-xSrxMnO3 (LSM) is a good cathode material or zirconia-based electrolyte, it shows high cathodic overpotential on LaGaO3-based electrolyte. The reaction between LSM and LaGaO3-based electrolyte was cited as a possible reason. When LSM was ccmposited with LaGaO3-based electrolyte and processed at low temperature, the much reduced cathodic overpotential was observed. When composite was used as a cathode on La0.9Sr0.1Ga0.8Mg0.2O3(LSGM) electrolyte for intermediate temperature SOFC, composite cathode showed better performarce with smaller IR drop and low cathodic overpotential than LSM cathode. However, the overpotential of fuel cell employing the LSM-LSGM composite cathode was still too high in spite of the improvement. In this study, La0.6Sr0.4CoO3 (LSC) was tested as a cathode or LaGaO3 since LSC has the higher mixed conductivity than LSM. The current interruption method was used to measure IR drop and thus to see the reaction between LSC and LaGaO3. LSC showed much reduced cathodic overpotential than LSM. A porous LSC-LSGM composite cathode coated on a dense LSGM electrolyte exhibited similar or slightly worse performance than LSC cathode. Thus the improvement using composite cathode is minimal for LSC-LSGM system.