Tungsten-Doped PrBaFe₂O_5+δ Double Perovskite as a High-Performance Electrode Material for Symmetrical Solid Oxide Fuel Cells

Abstract

Double perovskite PrBaFe 2 O 5+δ is a potential electrode material for symmetrical solid oxide fuel cells (Sym-SOFCs). This work aims to improve the Sym-SOFC performance by partially replacing Fe with W, forming a composition of (PrBa) 0.95 (Fe 0.95 W 0.05 ) 2 O 5+δ . Doping W keeps PrBaFe 2 O 5+δ stability after high-temperature treatment in both air and hydrogen atmospheres, decreases the thermal expansion coefficient from 17.11 × 10 −6 to 14.59 × 10 −6 K −1 , increases the content of oxygen species that are essential for the electrocatalytic reactions, and increases the chemical oxygen surface exchange coefficient by 121% at 800 °C. Consequently, doping W greatly improves the electrochemical performance, such as decreasing the areaspecific cathode polarization resistance by 35.5% to 0.031 Ω•cm 2 at 800 °C, reducing the anode polarization resistance by 17.7% to 0.123 Ω• cm 2 , and increasing the peak power density of Sym-SOFCs by 32.5% to 1.02 W cm −2 using humidified hydrogen as the fuel. The performance is much higher than those reported for Sym-SOFCs using PrBaFe 2 O 5+δ doped with the other elements. Finally, the Sym-SOFCs are capable of directly using hydrocarbon fuels, providing peak power densities of 0.610, 0.624, and 0.448 W cm −2 at 800 °C for syngas, ethane, and propane, respectively.

Characterization of Pr0.5A0.5Fe0.9W0.1O3−δ (A = Ca, Sr and Ba) as symmetric electrodes for solid oxide fuel cells

“…Therefore, in this work, the effect of divalent alkaline-earth metal dopants (Ca, Sr and Ba) doped on the A-site of tungsten-doped ferrite-based oxides (Pr 0.5 A 0.5 Fe 0.9 W 0.1 O 3Àd , PAFW) was investigated in terms of the phase structure and stability, electrochemical conductivity, thermal expansion and electro-catalytic activity including the mechanisms of the HOR and ORR, cell performance, and redox performance. Finally, according to the literature reports, 31 PrBaFe 2 O 5+d showed a double perovskite structure. We neglected the Pr 0.5 Ba 0.5 -Fe 0.9 W 0.1 O 3Àd (PrBaFe 1.8 W 0.2 O 5+d ) material in this work and will carefully investigate this material as a symmetric electrode for SSOFCs in the future.…”

Progress of Perovskites as Electrodes for Symmetrical Solid Oxide Fuel Cells

“…The PBF material has a large TEC (∼17.1–19.5 × 10 –6 K –1 in air), which does not match with the commonly used electrolytes. , Many efforts have been devoted to mitigating the thermomechanical mismatch problem. The introduction of dopants with good redox stability, such as W, could decrease the TEC from 17.1 × 10 –6 K –1 to 14.6 × 10 –6 K –1 for (PrBa) 0.95 (Fe 0.95 W 0.05 ) 2 O 5+δ , thus strengthening the interface bonding between electrode and electrolyte. The lanthanides, with different ionic radius and metal–oxygen bond strength, have a strong impact on the properties of LnBaFe 2 O 5+δ materials.…”

LaCrO3–CeO2-Based Nanocomposite Electrodes for Efficient Symmetrical Solid Oxide Fuel Cells

“…Different symmetrical electrodes have been reported in the literature, including doped LaCrO 3 , SrFeO 3 , PrBa­(Fe,Mn) 2 O 5+δ , and La 0.4 Sr 1.6 MnO 4+δ . − Among them, doped LaCrO 3 is one of the most widely studied due to its high redox stability, resistance to sulfur poisoning, and carbon coking, as well as chemical compatibility with the traditional Zr 0.84 Y 0.16 O 1.92 (YSZ) electrolyte. Different approaches have been developed to improve the electrocatalytic properties of LaCrO 3 -based electrodes, including doping in the A- or B-site of the perovskite (A = Ce, Bi and B = Mn, Fe, Ti), − and the introduction of highly active catalytic elements, such as Ni and Ru, which are exsolved on the electrode surface upon exposure to reducing atmospheres. , …”