Polarization and stability of La2NiO4+δ in comparison with La0.6Sr0.4Co0.2Fe0.8O3-δ as air electrode of solid oxide electrolysis cell

Solid oxide electrolysis cells (SOECs) are promising due to high electrolysis efficiency, but at high operating temperature T-OP >= 800 degrees C, they suffer from component inter-diffusion and particle agglomeration; selection of a sealant is also difficult. One way to avoid these problems is to decrease their Top. However, operation at intermediate T-OP similar to 650 degrees C limits SOEC efficiency due to high overpotential at the air electrode. We use La2NiO4+delta (LNO) as an air electrode (anode) of an SOEC and compare its electrochemical performance and stability with those of La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) in high-humidity H-2 atmosphere (80% H2O + 20% H-2) at Top = 650 degrees C. LNO and LSCF anodes are screen-printed on a Gd0.2Ce0.8O2-delta (GDC)/Y0.16Zr1.84O2-delta (8 mol % yttria-stabilized zirconia, YSZ) bilayer electrolytes of fuel electrode (cathode) supported cells. At open circuit condition, LSCF shows slightly smaller polarization resistance at 575 <= T-OP <= 800 degrees C and much slower degradation rate at Top = 650 degrees C than LNO for 150 h. In contrast, under high electrolysis current (-150 mA cm(-2)), the cell with LNO anode shows better electrochemical performance than that with LSCF anode. Thus, LNO is a promising anode for SOEC cells. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.