Electrochemical ageing study of mixed lanthanum/praseodymium nickelates La2-xPrxNiO4+δ as oxygen electrodes for solid oxide fuel or electrolysis cells

The chemical and electrochemical stability of lanthanide nickelates La2NiO4+delta (LNO), Pr2NiO4+delta (PNO) and their mixed compounds La2-xPrxNiO4+delta (LPNOs) with x = 0.5, 1 or 1.5 is reported. The aim is to promote these materials as efficient electrodes for solid oxide fuel cell (SOFC) and/or solid oxide electrolysis cell (SOEC). La2NiO4+delta and La1.5Pr0.5NiO4+delta compounds are chemically very stable as powders over one month in the temperature range 600 - 800 degrees C, while the other materials rich in praseodymium progressively decompose into various perovskite-deriving components with additional Pr6O11. Despite their uneven properties, all these materials are quite efficient and sustainable as electrodes on top of gadolinium doped ceria (GDC(BL)) // yttrium doped zirconia (8YSZ) electrolyte, for one month at 700 degrees C without polarization. Under polarization (300 mA.cm(-2)), the electrochemical performances of LNO, PNO and La1.5Pr0.5NiO4+delta (LP5NO) quickly degrade in SOFC mode, i.e. for the oxygen reduction reaction, while they show durability in SOEC mode, i.e. for the oxide oxidation reaction. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.