Performance of Ferrite-Based Electrodes for Steam Electrolysis in Symmetrical Solid Oxide Cells

Abstract

There is an increasing interest in the exploration of non-Nickel cathode materials for steam electrolysis in solid oxide electrolysis cells (SOEC) for green hydrogen production with high Faradaic efficiencies. Ferrite-based ceramic materials have drawn a lot of attention in this regard due to their appreciable mixed ionic electronic conductivity. This work aims to explore a ferrite-based mixed ionic electronic conductor electrode for symmetrical SOEC that can contribute significantly to simplifying the manufacturing processes. A composite of silver (Ag) and A-site deficient lanthanum strontium cobalt ferrite ((La_0.60Sr_0.40)_0.95Co_0.20Fe_0.80O_3-x), is studied for steam electrolysis in a yttria stabilized zirconia electrolyte-supported symmetrical tubular solid oxide cell. A considerable current density of 250 mA cm⁻² is obtained at 1.5 V and 800 °C in a Helium-Steam atmosphere (50% humidified) with a corresponding polarization resistance as low as 0.15 Ω-cm². The polarization resistance is comparable to a number of electrodes reported in the literature for steam electrolysis. However, a 10% drop in current density is observed during the first 20 h of electrolysis at 1.5 V and 800 °C in a Helium-Steam atmosphere (50% humidified), but no further drop is encountered during the next 46 h of continuous operation.