Evaluation of MIEC Ce_0.8Y_0.1Mn_0.1O_2-δAnode in Electrolyte-Supported SOFC

Abstract

In this study, the electrochemical performance of a single phase, mixed ion and electron conducting (MIEC) Ce 0.8 Y 0.1 Mn 0.1 O 2-δ (10CYMO) anode was evaluated using symmetrical half-cell and full-cell configurations under humidified H 2 , 10 ppm H 2 S/H 2 , and CH 4 . An yttria-stabilized zirconia (YSZ) electrolyte support layer was used in this work, as ac impedance spectroscopy revealed that the 10CYMO/YSZ/10CYMO cell gave the lowest area specific polarization resistance (ASR) of 0.23 cm 2 at 800 • C in wet H 2 , compared to La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) and Zr 0.89 Sc 0.1 Ce 0.01 O 2-δ (ScSZ). Exposure of the 10CYMO anodes to 10 ppm H 2 S/H 2 , either in a half-cell or full cell configuration, showed slight enhancement on the electrochemical performance, which was explained using a concept describing the sulfur and ceria interaction. Nickel and yttria-stabilized zirconia (Ni-YSZ) composite materials are used as anodes in solid oxide fuel cells (SOFCs) because they meet most of the key requirements, such as a high electrical conductivity of ∼10 3 Scm −1 , high catalytic activity for the hydrogen oxidation reaction (HOR), and thermal and chemical stability with YSZ at 700-1000• C. 1 Although the Ni-YSZ anode demonstrates good performance when H 2 is used as a fuel, this anode suffers from some drawbacks. These include a rapid deactivation of the Ni catalyst due to carbon deposition under hydrocarbon fuels.2 Also, adsorption of sulfur species that are present in hydrocarbon fuels on the Ni surface results in its poisoning due to a decrease in the electrochemically active area for the HOR.3 Furthermore, Ni coarsening 4 and redox instability 5 remain long-term issues in Ni-YSZ based SOFCs; therefore, immense work is in progress to find alternative anodes for advanced SOFCs. Perovskite and fluorite-type metal oxides have shown several interesting functional properties toward sulfur tolerance and coking that make them promising anodes for SOFCs.6 Acceptor-doped ceria exhibits mixed ion and electronic conduction (MIEC) in reducing conditions, which makes it suitable to be employed in anodes in intermediate temperature (IT) (500-750• C) SOFCs. 7 For example, Barnett et al. 8 showed that the addition of doped ceria to the Ni-YSZ anode resulted in a good SOFC performance with no deleterious coke formation at 600 • C in wet CH 4 . Nevertheless, the SOFC performance of doped ceria-based anodes in CH 4 was still significantly lower than in H 2 . 9,10 It is known that sulfur is present as H 2 S in many common fuels and is added as an odorant in commercial fuels, such as natural gas. Thus, the stability of SOFC anodes toward sulfur poisoning is an important parameter, especially for the commercialization of SOFCs, operating on a variety of fuels.3 Therefore, we have investigated the sulfur tolerance of ceria-based anodes, reporting that Ni infiltration into porous GDC yielded an anode that was stable in 10 ppm H 2 S. Also, B-site ordered double perovskite type tranisiton metals-doped Ba 3 CaNb 2 O 9 proved...

A Review on Perovskite-Type LaFeO3 Based Electrodes for CO2 Reduction in Solid Oxide Electrolysis Cells: Current Understanding of Structure–Functional Property Relationships

“…These MIEC materials demonstrate high catalytic activity, redox stability, and sulfur tolerance compared to Ni-YSZ. , Furthermore, several MIECs have demonstrated high stability in CO 2 /CO at an elevated temperature. − in which the entire surface is electrochemically active leading to a significant performance improvement, unlike cermet electrodes, due to MIEC–gas interface activity (dual-phase-boundary, DPB). Fluorite-type Ce 0.9 Gd 0.1 O 2−δ , perovskite-type LaFeO 3 , La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ , double perovskite-type Sr 2 MgMoO 6 , and Nd 2 WO 6 oxides are reported as potential electrodes for SOCs. − Among these families of MIECs, doped lanthanum ferrites were recently developed as SOEC cathodes due to their good catalytic activity, electronic conductivity, and oxygen mobility. − Since perovskite-type structure oxides are currently being widely explored, this article is aimed to provide an overview of LaFeO 3 electrodes for SOECs.…”

Desenvolvimento de célula a combustível de óxido sólido pelo método de colagem de fita e co-sinterização

“…Nas medidas de espectroscopia de impedância (Fig. Estudos prévios mostraram que as componentes de baixa e alta frequência da resistência de polarização de células a combustível são afetadas pela pressão parcial dos reagentes pO2 e pH2 [129,130]. A diminuição do semicírculo da alta frequência com os reagentes H2 e O2 indica que houve melhora em processos eletródicos associados a estas frequências, como a transferência de carga dos elétrons nas interfaces entre o eletrólito e o eletrodo [131].…”