Electrochemical performance of iron doped lanthanum strontium chromites as fuel electrodes in high temperature solid oxide cells

Abstract

The effect of B-site doping in perovskite-structure lanthanum strontium chromite La0.75Sr0.25CrO3-δ (LSCr) with 10 at.% (La0.75Sr0.25Cr0.9Fe0.1O3-δ, LSCrF0.1) and 50 at.% (La0.75Sr0.25Cr0.5Fe0.5O3-δ, LSCrF0.5) Fe in B (Cr) sublattice was studied with emphasis on the electronic conductivity under various gas compositions and the electrochemical activity of the materials as fuel electrodes in Solid Oxide Cells operating in reversible mode under a mixture of steam and hydrogen feed, and co-electrolysis of steam and carbon dioxide. Substitution of Cr by Fe had a negative effect on the electronic conductivity of the chromite, while on the other hand, it proved to be crucial for the electrochemical performance of the cell. Although LSCr exhibited higher electronic conductivity, it showed extremely poor electrochemical performance. The performance of electrolyte supported cells employing iron doped perovskites as fuel electrodes under H2O and/or CO2 electrolysis was almost the same, while the highest current densities of cells employing LSCrF0.1 fuel electrodes were evident in all processes evaluated. The fuel flexibility and high performance of LSCrF0.1 were demonstrated while further investigation is required in order to meet the long-term operation requirements.