Materials system for intermediate temperature (600-800°C) solid oxide fuel cells based on doped lanthanum-gallate electrolyte

Abstract

AC complex impedance spectroscopy studies were conducted between 600-800°C on symmetrical cells that employed LSGM electrolyte. The objective of the study was to identify the materials system for fabrication and evaluation of intermediate temperature SOFCs. Cathode materials investigated include LSM, LSCF, LSM-LSGM, and LSCF-LSGM composites. The anode materials were Ni-GDC and Ni-LDC composites. Experiments conducted with the anode materials investigated the effect of having a barrier layer of GDC or LDC in between the LSGM electrolyte and the Ni-composite anode to prevent adverse reaction of the Ni with lanthanum in LSGM. The ohmic and the polarization resistances of the system were obtained over time as a function of temperature, firing temperature, thickness, and the composition of the electrodes. The study revealed important details pertaining to the ohmic and the polarization resistances of the electrode as they relate to stability and the charge-transfer reactions that occur in such electrode structures.