La2NiO4 + δ as electrode material for solid oxide fuel cells and electrolyzer cells

In this work, the mixed ionic-electronic conducting ceramic La2NiO4 + δ is investigated with respect to its applicability as SOFC cathode as well as SOEC anode material on the basis of electrolyte-supported button cells. Results are obtained by electrochemical impedance spectroscopy and current-voltage analyses on symmetrical cells with screen printed La2NiO4 + δ electrodes under both anodic and cathodic polarization, where special emphasis is put on the chromium tolerance of the material. The long-term behavior of electrodes in pure oxygen/argon as well as in humidified chromium-containing atmospheres is studied at 800 °C both under open circuit conditions and with applied current load. Once a chromium source is introduced in humid conditions, a strong decline in the cell performance occurs which can be mainly ascribed to a deactivation of the SOFC cathode layer. Post-test analytical investigations of cell cross sections by SEM and TEM suggest differences in the extent of Cr-contamination to be the main factor for the pronounced discrepancy between degradation rates of both electrodes.