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

Abstract Solid oxide electrolysis cells (SOECs) are promising due to high electrolysis efficiency, but at high operating temperature T OP  ≥ 800 °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 T OP . However, operation at intermediate T OP ∼650 °C limits SOEC efficiency due to high overpotential at the air electrode. We use La 2 NiO 4+δ (LNO) as an air electrode (anode) of an SOEC and compare its electrochemical performance and stability with those of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) in high-humidity H 2 atmosphere (80% H 2 O + 20% H 2 ) at T OP  = 650 °C. LNO and LSCF anodes are screen-printed on a Gd 0.2 Ce 0.8 O 2−δ (GDC)/Y 0.16 Zr 1.84 O 2−δ (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 °C and much slower degradation rate at T OP  = 650 °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.