Efficient Ferrite-Based Perovskite Anode for Solid Oxide Fuel Cells with A-Site and B-Site Co-exsolution

Abstract

Exsolution of A-site and/or B-site dopants has been widely used to improve the electroactivity and coking resistance of the perovskite anode for solid oxide fuel cells (SOFCs). Here, an A-site and B-site co-exsolved Ba0.3Sr0.7Fe0.9Mn0.1O3−δ (BSFM) perovskite is employed as the anode material of SOFCs. X-ray diffraction results confirm that the cubic BSFM perovskite shows reasonable structure stability in hydrogen, although metallic Fe and SrO exsolve from the provskite lattice. Scanning electron microscopy results find that a whisker-like species grows from the perovskite in addition to the exsolution of Fe nanoparticles. It is verified by transmission electron microscopy–energy-dispersive X-ray spectroscopy that the whisker is composed of BaO and SrO. The surface enrichment of Ba and Sr elements is also proven by X-ray photoelectron spectroscopy. The peak power densities of a single cell with the BSFM anode are 538 and 364 mW cm–2 at 800 and 750 °C in hydrogen, respectively, while the polarization resistances of them are 0.18 and 0.28 Ω cm2 at the same conditions, respectively. The cell operates stably for over 60 h in hydrogen with a current density of 0.2 A cm–2. However, the BSFM anode shows sluggish activity for methane oxidation. With the addition of Ni to the BSFM anode, its activity for methane oxidation is remarkably improved, and the peak power density increases from 84 mW cm–2 for the BSFM anode to 194 mW cm–2 for the Ni–BSFM anode at 800 °C in methane. The Ni–BSFM anode also exhibits excellent stability in methane and works stably for over 70 h with a current density of 0.2 A cm–2.

In Situ Exsolved NiFe/(NiFe)Ox Core–Shell-Structured Nanocatalysts on Perovskite Anode with Enhanced Coking Resistance

“…The open circuit voltage (OCV) of the single cell is 1.054 V at 800 °C. The single cell reaches a maximum power density ( P max ) of 1099 mW cm –2 in wet H 2 at 800 °C, which is much higher than that of the single cell with SrFeO 3 -based perovskite anodes, for example, Sr 0.95 (Ti 0.3 Fe 0.63 Ni 0.07 )­O 3‑δ , La 0.6 Sr 0.4 Fe 0.95 Pd 0.05 O 3‑δ , and Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3−δ . ,, Electrochemical impedance spectra (EIS) of a single cell with the BSNFM-NFA/NFO anode and LSCF-GDC cathode at different temperatures are shown in Figure d. In these spectra, the intercepts of the impedance arcs with the real axis at high frequency are attributed to the ohmic resistance (R o ) mainly originating from the electrolyte and electrolyte/electrode interface.…”

“…Therefore, it is significant to select an anode material with excellent catalytic activity for hydrogen (H 2 ) and hydrocarbon fuels and favorable carbon coking resistance for the development of high performance SOFCs. Various ceramic anode materials have been investigated, such as metal fluorite cermets (Co 0.5 Fe 0.5 Sm 0.2 Ce 0.8 O 1.9 and SnNi-Gd 0.1 Ce 0.9 O 1.95 ), , cubic perovskites (La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3 , Sr 0.95 (Ti 0.3 Fe 0.63 Ni 0.07 )­O 3‑δ , Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3−δ , and Sr 0.88 Y 0.8 TiO 3 ), − double perovskites (Sr 2 MgMoO 6‑δ and Sr 2 FeMoO 6 ), , layered perovskites (PrBaMnO 5+δ ), and pyrochlore-structured materials (Ba 7 Y 2 Mn 3 Ti 2 O 20 ) . Among them, SrFeO 3 -based perovskites have been extensively studied as SOFC anode materials for their remarkable electron and oxygen ion (O 2– ) conductivity .…”

“…0 7 )O 3δ , La 0.6 Sr 0.4 Fe 0.95 Pd 0.05 O 3-δ , and Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3−δ . 12,28,48 Electrochemical impedance spectra (EIS) of a single cell with the BSNFM-NFA/NFO anode and LSCF-GDC cathode at different temperatures are shown in Figure 3d. In these spectra, the intercepts of the impedance arcs with the real axis at high frequency are attributed to the ohmic resistance (R o ) mainly originating from the electrolyte and electrolyte/ electrode interface.…”

Virtual Special Issue of Research Highlights on Sustainable Energy and Clean Fuels at State Key Laboratory of Materials-Oriented Chemical Engineering (SKL-MCE), China

“…Three papers are included on this topic. Zhao et al 19 report an A-and B-site co-exsolved Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3−δ (BSFM) perovskite with surface-decorated Fe and BaO/SrO as the anode material for SOFCs. The cell with this composite BSFM anode shows a high power output and stability in H 2 fuel, while the electrocatalytic activity of BSFM for methane oxidation is remarkably improved by the addition of Ni through infiltration.…”

In Situ Coexsolution of Metal Nanoparticle-Decorated Double Perovskites As Anode Materials for Solid Oxide Fuel Cells

“…The catalytic performance of an anode can be improved according to the type and size of the metal used in the in situ exsolution process. For example, under reducing conditions, Pd, Fe, Co–Fe alloy, and Co–Ni alloy precipitate from La 0.6 Sr 0.4 Fe 0.85 Pd 0.05 Mn 0.1 O 3 , Ba 0.3 Sr 0.7 Fe 0.9 Mn 0.1 O 3−δ , Pr 0.4 Sr 0.6 Co 0.2 Fe 0.7 Nb 0.1 O 3−δ , and PrBaMn 1.7 Co 0.1 Ni 0.2 O 5+δ , respectively, − with most of these metal nanoparticles being uniformly precipitated on the surfaces of the anodes. When Pr 0.4 Sr 0.6 Co 0.2 Fe 0.7 Nb 0.1 O 3−δ is used as an anode, its maximum power density is 0.60 W cm –2 using wet CH 4 as a fuel at 850 °C and 0.92 W cm –2 using C 3 H 8 at the same temperature .…”