Investigations on chemical interactions between alternate cathodes and lanthanum gallate electrolyte for intermediate temperature solid oxide fuel cell (ITSOFC)

The doped perovskite oxides such as La0.65Sr0.30MnO3-delta (LSM), La0.70Sr0.30CoO3-delta (LSC), La0.65Sr0.30FeO3-delta (LSF), La0.65Sr0.30NiO3-delta (LSN) and La0.60Sr0.40Co0.20Fe0.80O3-delta (LSCF) are proposed as alternate cathode materials for solid oxide fuel cells working at reduced temperature (< 1073 K). The critical requirement for their applicability is their chemical compatibility in conjunction with an alternate solid electrolyte, La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) without any new phase formation. To understand the chemical reactivity between these two components, thoroughly mixed different cathode and LSGM electrolyte (1:1 by wt.) powders were pressed as circular components and subjected to annealing at 1573 K for 3 h in air. XRD and SEM were used for the characterization of the annealed samples. XRD measurements revealed that no new secondary phases were formed in LSM, LSC, and LSF with LSGM mixtures whereas LSN and LSCF with LSGM resulted in the formation of new secondary phases after high temperature treatment. The sintering shrinkage for all the components (cathode + electrolyte mixture) was also estimated. For comparison of data, the individual powders (cathode/electrolyte) were also compacted and studied in the same manner. The obtained results are discussed keeping in view the requirements that the candidate cathode material must meet out with respect to its chemical compatibility to qualify for the LSGM based ITSOFC systems at 1073 K.