Co-synthesis of LSCFN-GDC electrode for symmetric solid oxide fuel cell running on propane

Performance optimization of metal-supported solid oxide fuel cells using cathode and full cell impregnation with La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ electrode

In this study, precursor solutions of La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ (LSCFN) symmetric electrode were prepared, and the applications of cathode impregnation and full cell impregnation in the preparation and performance optimization of four-layer metal-supported solid oxide fuel cells (MSCs) were thoroughly investigated. Test results indicate that the polarization impedance of cathode impregnated MSCs under H2 and CH4 atmospheres at 750 °C is approximately 0.1 Ω cm2 and 0.41 Ω cm2, respectively, with power densities of 1115 mW cm-2 and 700 mW cm-2, respectively. Meanwhile, the polarization impedance of full cell impregnated MSCs under the same conditions is 0.12 Ω cm2 and 0.40 Ω cm2, with power densities of 945 mW cm-2 and 840 mW cm-2, respectively. Remarkably, MSCs full cell impregnated LSCFN exhibit outstanding stability performance under CH4 atmosphere in a 100 h stability test. Research on the application of impregnation method for performance optimization of metal-supported cells is relatively scarce. The results reveal the feasibility of simplifying MSCs preparation steps using full cell impregnation method, further promoting the widespread application of metal-supported overall cells.

Mechanistic Study on the Corrosion of (La,Sr)(Co,Fe)O3-δ Cathodes Induced by CO2

Solid Oxide Fuel Cell (SOFC) cathodes operating in ambient atmospheric conditions inevitably encounter CO2 contamination, leading to sustained performance deterioration. In this investigation, we examined the impact of CO2 on three variants of (La,Sr)(Co,Fe)O3-δ cathodes and employed the distribution of relaxation times method to distinguish distinct electrochemical processes based on impedance spectra analysis. We meticulously analyzed and discussed the corrosion resistance of these (La,Sr)(Co,Fe)O3-δ cathodes under high CO2 concentrations, relying on the experimental data. Electrochemical impedance spectroscopy results revealed that La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428), La0.4Sr0.6Co0.2Fe0.8O3-δ (LSCF-4628), and La0.4Sr0.6Co0.2Fe0.7Nb0.1O3-δ (LSCFN-46271) cathodes exhibited persistent degradation when exposed to CO2 at temperatures of 650 °C or 800 °C during the durability-testing period. An increase in electrode polarization resistance was observed upon CO2 introduction to the electrode, but electrode performance recovered upon returning to a pure air environment. Furthermore, X-ray diffraction and scanning electron microscopy analyses confirmed that CO2 did not cause permanent damage to the (La,Sr)(Co,Fe)O3-δ cathodes. These findings indicate that the (La,Sr)(Co,Fe)O3-δ cathodes exhibit excellent resistance to CO2-induced corrosion.

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

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.

Excellent Electrochemical Performance of La0.3Sr0.7Fe0.9Ti0.1O3-δ as a Symmetric Electrode for Solid Oxide Cells

Solid oxide cells (SOCs) can switch between fuel cell and electrolysis cell modes, which alleviate environmental and energy problems. In this study, the La_0.3Sr_0.7Fe_0.9Ti_0.1O_3-δ (LSFTi 91) perovskite is innovatively used as a symmetric electrode for solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). LSFTi 91 exhibits a pure perovskite phase in both oxidizing and reducing atmospheres, and the maximum conductivity in air and 5% H₂/Ar is 150 and 1.1 S cm^-1, respectively, which meets the requirement of the symmetric electrode. The polarization resistance (R_p) at 1.5 V is as low as 0.09 Ω cm² in the SOEC mode due to the excellent CO₂ adsorption capacity. The current density can reach 1.9 A cm^-2 at 1.5 V and 800 °C, which is the highest electrolytic performance in the reported single-phase electrodes. LSFTi 91 also exhibits eminent oxygen reduction reaction and hydrogen oxidation reaction (ORR and HOR) activities, with R_p of 0.022 and 0.15 Ω cm² in air and wet H₂, respectively. The peak power density of SOFC could reach 847 mW cm^-2 at 800 °C. In addition, good reversibility is confirmed in the cyclic operation of SOFC and SOEC.