Sintering Aid Strategy for Promoting Oxygen Reduction Reaction on High-Performance Double-Layer LaNi0.6Fe0.4O3-δ Composite Electrode for Devices Based on Solid-State Membranes.

Abstract

Strontium and cobalt-free LaNi0.6Fe0.4O3-δ is considered one of the most promising electrodes for solid-state electrochemical devices. LaNi0.6Fe0.4O3-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 LaNi0.6Fe0.4O3-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 LaNi0.6Fe0.4O3-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 (Bi0.75Y0.25O2-δ and CuO) in the collector layer on the performance of LaNi0.6Fe0.4O3-δ-based highly active electrodes in contact with the most common solid-state membranes (Zr0.84Sc0.16O2-δ, Ce0.8Sm0.2O2-δ, La0.85Sr0.15Ga0.85Mg0.15O3-δ, La10(SiO4)6O3-δ, and BaCe0.89Gd0.1Cu0.01O3-δ) was investigated. It was shown that LaNi0.6Fe0.4O3-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.% Bi0.75Y0.25O1.5 and 2 wt.% CuO in the collector layer.