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This paper is dedicated to the impact of pressure on the electrochemical behaviour of LSCF (La1-xSrxCoyFe1-yO3-δ) anode in high-temperature electrolysers. This study was carried out with symmetrical cells associating LSCF electrodes to a 3YSZ (yttrium-stabilised zirconia) electrolyte. Impedance spectroscopy measurements were performed using a three-electrode configuration, at temperature as high as 700 to 800 °C, in a pressure range from 1 to 30 bar. A clear improvement in terms of electrode resistance decrease is highlighted, mainly due to faster oxygen adsorption/desorption kinetics and a better supply of gas to electrochemical reaction sites. Other assumptions were considered and analysed, such as the impact of pressure on LSCF electrical conductivity and on the mechanical contacts. Thus, three contributions were determined as limiting steps at low pressure, up to 5 bar, whilst for higher pressure, the optimised conditions in operation are reached. This study completes a previous one related to a modelling approach. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]