A-site deficient (La0.6Sr0.4)1–x Co0.2Fe0.6Nb0.2O3–δ symmetrical electrode materials for solid oxide fuel cells

Highlights: • LSCFN-based electrodes exhibit excellent structural stability in air and 5% H₂/Ar. • LSCFN-based electrodes are chemical compatibility with LSGM and SDC electrolytes. • LSCFN10 electrode shows more superior electrochemical stability than LSCF material. • Single cell with LSCFN10 electrode can operate on various fuels of CH₄, syngas and ethanol. A-site deficient (La_0.6Sr_0.4)_1–xCo_0.2Fe_0.6Nb_0.2O_3–δ (x = 0, 0.05 and 0.10) symmetrical electrodes (hereafter denoted as LSCFN, LSCFN5, and LSCFN10, respectively) are obtained by doping Nb at the B site of La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ (LSCF) cathode. All three electrodes display excellent structural stability both in cathode and anode conditions. The thermal expansion coefficients of the electrodes range within 13.4–14.3 × 10⁻⁶ K⁻¹ at 30–900 °C in air and 5% H₂/Ar, and these values are close to those of common electrolytes. Furthermore, 20-h electrochemical impedance stability test results indicate that LSCFN10 as anode or cathode possesses excellent electrochemical stability. The introduction of A-site deficiency into LSCFN results in obviously increased oxygen–vacancy concentration and improved electrochemical performance. A single cell with LSCFN10 symmetrical electrode operates well in various fuels, such as H₂, sulfur-containing syngas, ethanol, and CH₄, and shows favorable electrochemical stability running on CH₄ fuel.