Influence of Hydrogen Electrode Active Layer Thickness on Electrochemical Performance of Solid Oxide Cell Operating in Electrolysis Mode

Abstract

Reversible solid oxide cell technology (RSOC) is a key technology in future hydrogen energy concepts and may play a significant role in stabilizing intermittent renewable electric power sources. Here we report an attempt to optimize the thickness of the hydrogen electrode active layer (HEAL) for solid oxide cells designed and developed initially for fuel cell application. Five cells with HEAL thickness of 0, 7, 12, 16, and 20 µm, prepared using industrial manufacturing methods, are analyzed using cyclic voltammetry and electrochemical impedance spectroscopy methods under a wide range of operating conditions. Optimal thickness of an active layer studied depends on operating conditions. Depending on the temperature and humidity applied highest performances were achieved for cells with HEAL thicknesses between 7 and 16 µm. At 800°C and 90% feed gas water content, the best cell had an active layer of 7 µm, drawing -3.5 A/cm2 current at -1.4 V.