Performance of La 2– x Sr x Co 0.5 Ni 0.5 O 4±δ as an Oxygen Electrode for Solid Oxide Reversible Cells

La 2 – x Sr x Co 0.5 Ni 0.5 O 4 ± δ (LSCN) is presented as a novel electrode for both solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). LSCN/10Sc1CeSZ (scandia and ceria stabilised zirconia)/LSCN symmetrical cells were fabricated and characterised by AC impedance spectroscopy under different oxygen partial pressures at temperatures of up to 900 °C. At 850 °C polarisation resistances of 5.15 and 5.74 Ω cm 2 were found applying air and oxygen, respectively. Electrolysis and fuel cell j –V experiments were also performed at temperatures between 700 and 850 °C using a LSCN/10Sc1CeSZ/Ni‐YSZ. Electrochemical results showed that the cell performs equally in both SOFC and SOEC modes. Detailed results in terms of performance are presented and discussed. LSCN is presented as a good candidate for both SOFC and SOEC. The similar performance obtained for j – V (current density–voltage) curves in electrolysis and fuel cell operation mode is thought to be related to the flexible oxygen non‐stoichiometry of the LSCN (K 2 NiF 4 ‐type structure).