Cathode microstructure control and performance improvement for low temperature solid oxide fuel cells

Abstract

In order to fabricate a highly performing cathode for low-temperature type solid oxide fuel cells working at below 700°C, electrode microstructure control and electrode polarization measurement were performed with an electronic conductor, La0.8Sr0.2MnO3 (LSM) and a mixed conductor, La0.6Sr0.4Co0.2Fe 0.8O3 (LSCF). For both cathode materials, when Sm 0.2Ce0.8O2 (SDC) buffer layer was formed between the cathode and yttria-stabilized zirconia (YSZ) electrolyte, interfacial reaction products were effectively prevented at the high temperature of cathode sintering and the electrode polarization was also reduced. Moreover, cathode polarization was greatly reduced by applying the SDC sol-gel coating on the cathode pore surface, which can increase triple phase boundary from the electrolyte interface to the electrode surface. For the LSCF cathode with the SDC buffer layer and modified by the SDC sol-gel coating on the cathode pore surface, the cathode resistance was as low as 0.11 Ω-cm2 measured at 700°C in air atmosphere.