Enhanced Performances of Ln2NiO4+δ / CGO Multilayered Anodes for High Temperature Steam Electrolysis (HTSE)

Abstract

Multilayered oxygen electrodes for High Temperature Steam Electrolysis (HTSE) based on nickelate oxides Ln2NiO4+δ (Ln=La, Pr or Nd) as active material and gadolinium-doped ceria (CGO) as buffer layer have been characterized on symmetrical half-cells with yttria-stabilized zirconia (YSZ) as electrolyte. The polarization resistances (Rp) were measured by electrochemical impedance spectroscopy, between 600°C and 800°C. The Rp values of Pr2NiO4+δ/CGO multilayered electrodes are 3 times lower compared to those obtained with cells without CGO layer. At 800°C, Rp values of Ln2NiO4+δ/YSZ-based cells are about 0.14-0.20 Ω.cm² whereas the Rp of Pr2NiO4+δ/CGO/YSZ-based cell is reduced till 0.04 Ω.cm². Using a three-electrode setup, anodic overpotentials were obtained. Polarization curves evidence larger current densities for a given overpotential with cells containing the CGO interface. These results seem to show that multilayered materials based on nickelates Ln2NiO4+δ and CGO are particularly suitable for a use as oxygen electrode for HTSE.