Sintering Aid Strategy for Promoting Oxygen Reduction Reaction on High-Performance Double-Layer LaNi_0.6Fe_0.4O_3-δ...

Strontium and cobalt-free LaNi_0.6Fe_0.4O_3-δ is considered one of the most promising electrodes for solid-state electrochemical devices. LaNi_0.6Fe_0.4O_3-δ has high electrical conductivity, a suitable thermal expansion coefficient, satisfactory tolerance to chromium poisoning, and chemical compatibility with zirconia-based electrolytes. The disadvantage of LaNi_0.6Fe_0.4O_3-δ is its low oxygen-ion conductivity. In order to increase the oxygen-ion conductivity, a complex oxide based on a doped ceria is added to the LaNi_0.6Fe_0.4O_3-δ. However, this leads to a decrease in the conductivity of the electrode. In this case, a two-layer electrode with a functional composite layer and a collector layer with the addition of sintering additives should be used. In this study, the effect of sintering additives (Bi_0.75Y_0.25O_2-δ and CuO) in the collector layer on the performance of LaNi_0.6Fe_0.4O_3-δ-based highly active electrodes in contact with the most common solid-state membranes (Zr_0.84Sc_0.16O_2-δ, Ce_0.8Sm_0.2O_2-δ, La_0.85Sr_0.15Ga_0.85Mg_0.15O_3-δ, La₁₀(SiO₄)₆O_3-δ, and BaCe_0.89Gd_0.1Cu_0.01O_3-δ) was investigated. It was shown that LaNi_0.6Fe_0.4O_3-δ has good chemical compatibility with the abovementioned membranes. The best electrochemical activity (polarization resistance about 0.02 Ohm cm² at 800 °C) was obtained for the electrode with 5 wt.% Bi_0.75Y_0.25O_1.5 and 2 wt.% CuO in the collector layer.