Perovskite-Based Materials As Alternative Fuel Electrodes for Solid Oxide Electrolysis Cells (SOECs)

Abstract

Perovskites show high potential as alternative fuel electrodes in solid oxide electrolysis cells (SOECs) due to their high chemical stability, high conductivity, good catalytic activity and cost-effectiveness. In this work, four perovskites (strontium-iron-niobate double perovskite (SFN), strontium-iron-titanate (STF), lanthanum-strontium-titanate (LST), and lanthanum-strontium-iron-manganese (LSFM)) were examined as fuel electrode materials for SOECs. First, the chemical stability of the perovskites in a reducing atmosphere and the reactivity between the electrode and electrolyte material were analyzed. Besides featuring good chemical stability under reducing conditions, SFN double perovskite and LST exhibit the lowest interaction with the electrolyte (yttria-stabilized zirconia, 8YSZ) after thermal treatment. The results indicate a need for a barrier layer between the tested electrode materials and the YSZ electrolyte to achieve sufficient cell performance throughout its operation in the electrolysis mode. After thoroughly evaluating all preliminary tests, STF was chosen for the first subsequent electrochemical tests. Initial impedance measurements of symmetrical electrolyte-supported cells consisting of pure STF-based electrodes with and without a barrier layer between the electrodes and the electrolyte were conducted to obtain a base for further optimization. For the 5STF fuel electrode, the obtained EIS data confirm the conclusion from the reactivity experiments. Applying a barrier layer at the 5STF fuel electrode/ electrolyte interface is needed to reduce the cell´s ohmic and polarization resistances.