Strontium Free Cu-Doped La2NiO4 Oxides as Promising Oxygen Electrodes for Solid Oxide Electrolysis Cells

Abstract

In this work, strontium-free copper-doped nickelates, La2Ni1-xCuxO4 (x=0.1-0.3), were synthesized using solid state synthesis method and tested as potential oxygen electrodes in solid oxide electrolysis cells (SOEC). Similar to the parent compound, the Ruddlesden-Popper (RP) La2NiO4 oxide, the Cu-doped compositions were confirmed to crystallize with tetragonal crystal structure with I4/mmm space group. The electrochemical performance of La2Ni1-xCuxO4 electrodes was studied using Ni-YSZ electrode-supported button cells in SOEC mode and compared to the state-of-the-art (La0.6Sr0.4)0.95Co0.0.8O3-δ (LSCF)-doped ceria composite electrodes. Electrochemical tests were conducted at 750oC with the Ni-YSZ hydrogen electrode exposed to 50% steam in hydrogen. The polarization resistance of SOEC with the La2Ni0.8Cu0.2O4 (LNCuO-20) electrode was lower than that with LSCF. LNCuO-20 showed stable current density output over 800 hours tested, while cell with LSCF showed more degradation.