Effect of pressure on high temperature steam electrolysis: Model and experimental tests

In order to improve the industrial attractiveness of high temperature steam electrolysis (HTSE), increasing the operating pressure is one of the most promising solutions. In this context, this study is dedicated to the analysis of the pressure influence on the electrochemical reactions occurring in HTSE. The behavior of half-cells constituted by YSZ electrolytes and Ni/YSZ cathodes or LSCF anodes was simulated by COMSOL multiphysics®. This model highlights that the limiting current density due to the lack of steam is shifted towards higher steam conversion rates by increasing the operating pressure, without negative thermodynamic effect at high current density. Furthermore, the overpressure at the oxygen electrode/electrolyte interface decreases with the operating pressure and, therefore, the risk of delamination is reduced. Experimentally, a positive effect of pressure on the oxygen side performances was observed, contrarily to the model calculation.