Enhanced oxygen electrode kinetics at low temperatures: an infiltrated Sr(Ti0.3Fe0.55Co0.15)O3-δ–La0.8Sr0.2Ga0.8Mg0.2O3-δ nanocomposite for solid oxide cells

Abstract

Low-temperature (≤650 °C) solid oxide cells hold great potential for next-generation fuel cells and electrolyzers. Although Sr- and Mg-doped LaGaO₃ (LSGM) is a promising electrolyte for this purpose, developing an electrode that meets all the performance, stability, and compatibility criteria remains challenging. Herein, we report a high-performance nanocomposite oxygen electrode fabricated by infiltrating a porous LSGM framework with the Sr(Ti_0.3Fe_0.55Co_0.15)O_3-δ (STFC) catalyst, noted for its excellent oxygen transport properties and surface stability. This novel STFC–LSGM electrode, composed of ∼80.1 vol% LSGM and ∼4.2 vol% STFC, exhibits an exceptionally low polarization resistance of ∼0.06 Ω cm² at 600 °C, with a degradation of ∼11.2% per 1000 h under open-circuit conditions. The mechanisms behind this remarkable performance and stability are investigated via impedance analysis using a microstructure-coupled transmission-line model. Integrated into a full cell with a thin LSGM electrolyte and a Sr_0.8La_0.2TiO_3-δ support, the optimized electrode delivers impressive performance, achieving a fuel cell power density of ∼1.54 W cm⁻² and a steam electrolysis current density at 1.3 V of ∼1.37 A cm⁻², both at 600 °C. This work demonstrates a promising route for developing high-performance oxygen electrodes for LSGM-based SOC applications.