Modulating the Energy Band Structure of the Mg-Doped Sr0.5Pr0.5Fe0.2Mg0.2Ti0.6O3-δ Electrolyte with Boosted Ionic Conductivity and Electrochemical Performance for Solid Oxide Fuel Cells

Smart Dual-Exsolved Self-Assembled Anode Enables Efficient and Robust Methane-Fueled Solid Oxide Fuel Cells

Perovskite oxides have emerged as alternative anode materials for hydrocarbon-fueled solid oxide fuel cells (SOFCs). Nevertheless, the sluggish kinetics for hydrocarbon conversion hinder their commercial applications. Herein, a novel dual-exsolved self-assembled anode for CH4 -fueled SOFCs is developed. The designed Ru@Ru-Sr2 Fe1.5 Mo0.5 O6-δ (SFM)/Ru-Gd0.1 Ce0.9 O2-δ (GDC) anode exhibits a unique hierarchical structure of nano-heterointerfaces exsolved on submicron skeletons. As a result, the Ru@Ru-SFM/Ru-GDC anode-based single cell achieves high peak power densities of 1.03 and 0.63 W cm-2 at 800 °C under humidified H2 and CH4 , surpassing most reported perovskite-based anodes. Moreover, this anode demonstrates negligible degradation over 200 h in humidified CH4 , indicating high resistance to carbon deposition. Density functional theory calculations reveal that the created metal-oxide heterointerfaces of Ru@Ru-SFM and Ru@Ru-GDC have higher intrinsic activities for CH4 conversion compared to pristine SFM. These findings highlight a viable design of the dual-exsolved self-assembled anode for efficient and robust hydrocarbon-fueled SOFCs.

Improved Ionic Transport Using a Novel Semiconductor Co0.6Mn0.4Fe0.4Al1.6O4 and Its Heterostructure with Zinc Oxide for Electrolyte Membrane in LT-CFCs

Improving the ionic conductivity and slow oxygen reduction electro-catalytic activity of reactions occurring at low operating temperature would do wonders for the widespread use of low-operating temperature ceramic fuel cells (LT-CFCs; 450-550 °C). In this work, we present a novel semiconductor heterostructure composite made of a spinel-like structure of Co_0.6Mn_0.4Fe_0.4Al_1.6O₄ (CMFA) and ZnO, which functions as an effective electrolyte membrane for solid oxide fuel cells. For enhanced fuel cell performance at sub-optimal temperatures, the CMFA-ZnO heterostructure composite was developed. We have shown that a button-sized SOFC fueled by H₂ and ambient air can provide 835 mW/cm² of power and 2216 mA/cm² of current at 550 °C, possibly functioning down to 450 °C. In addition, the oxygen vacancy formation energy and activation energy of the CMFA-ZnO heterostructure composite is lower than those of the individual CMFA and ZnO, facilitating ion transit. The improved ionic conduction of the CMFA-ZnO heterostructure composite was investigated using several transmission and spectroscopic measures, including X-ray diffraction, photoelectron, and UV-visible spectroscopy, and density functional theory (DFT) calculations. These findings suggest that the heterostructure approach is practical for LT-SOFCs.

Improving the electrochemical energy conversion of solid oxide fuel cells through the interface effect in La0.6Sr0.4Co0.2Fe0.8O3-δ-BaTiO3-δ electrolyte

Herein, we present a heterostructure electrolyte with considerable potential for application in low-temperature solid oxide fuel cells (LT-SOFCs). Heterostructure electrolytes are advantageous because the multiphase interfaces in their heterostructures are superior for ion conduction than for bulk conduction. Most previous studies on heterostructure electrolytes explained the influence of interfacial parameters on ion conduction in terms of the space charge zones and lattice mismatch, neglecting the characterization of the interface. In this study, a series of heterostructure electrolytes comprising La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) and BaTiO_3-δ (BTO) with different composition ratios was developed. Further, the lattice mismatch due to thermal stress in this system was evaluated by thermal expansion and electron energy loss spectroscopy (EELS) analyses. Results indicated that 7LSCF-3BTO produced the narrowest interface and the most surface oxygen vacancies, suggesting that the stress generated by thermal expansion increased the density of the interface. The cell with the optimal 7LSCF-3BTO composition delivered a peak power density of 910mW cm^-2 and an open circuit voltage of 1.07 V at 550 °C. The heterojunction effect was studied to elucidate the prevention of short circuiting in the LSCF-BTO cell, considering the Femi level and barrier energy height. This study provides novel ideas for the design of electrolytes for LT-SOFCs from the interface perspective.