• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.345-350
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• 2018

Nanomaterials have considerable potential to solve several key challenges in various electrochemical devices, such as fuel cells. However, the use of nanoparticles in high-temperature devices like solid-oxide fuel cells (SOFCs) is considered problematic because the nanostructured surface typically prepared by deposition techniques may easily coarsen and thus deactivate, especially when used in high-temperature redox conditions. Herein we report the synthesis of a self-regenerated Pd metal nanoparticle on the perovskite oxide anode surface for SOFCs that exhibit self-recovery from their degradation in redox cycle and $CH_4$ fuel running. Using Pd-doped perovskite, $La(Sr)Fe(Mn,Pd)O_3$, as an anode, fairly high maximum power densities of 0.5 and $0.2cm^{-2}$ were achieved at 1,073 K in $H_2$ and $CH_4$ respectively, despite using thick electrolyte support-type cell. Long-term stability was also examined in $CH_4$ and the redox cycle, when the anode is exposed to air. The cell with Pd-doped perovskite anode had high tolerance against re-oxidation and recovered the behavior of anodic performance from catalytic degradation. This recovery of power density can be explained by the surface segregation of Pd nanoparticles, which are self-recovered via re-oxidation and reduction. In addition, self-recovery of the anode by oxidation treatment was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.296-301
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• 2023

Solid oxide fuel cell has received more attention recently due to the fuel flexibility via internal reforming. Commonly used Ni/YSZ anode, however, can be easily deactivated by carbon coking in hydrocarbon fuels. The carbon deposition problem can minimize by developing alternative perovskite anode. This study is focused on improving conductivity and catalytic activity of the perovskite anode by introducing rGO (reduced graphene oxide). Sr_0.92Y_0.08TiO₃(SYT) anode with perovskite structure was synthesized with 1wt% of rGO. The presence of rGO during anode fabricating process and cell operation is confirmed through XPS and Raman analysis. The maximum power density of rGO/SYT anode improved to 3 times in H₂ and 6 times in CH₄ comparing to that of SYT anode due to the high electrical conductivity and good catalytic activity for CH₄.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.226-240
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• 2023

This paper provides an overview of the trends and future directions in the development of anode materials for solid oxide fuel cells (SOFCs) using hydrocarbons as fuel, with the aim of enabling a decentralized energy supply. Hydrocarbons (such as natural gas and biogas) offer promising alternatives to traditional energy sources, as their use in SOFCs can help meet the growing demands for energy. We cover several types of materials, including perovskite structures, high-entropy alloys, proton-conducting ceramic materials, anode on-cell catalyst reforming layers, and anode functional layers. In addition, we review the performance and long-term stability of cells based on these anode materials and assess their potential for commercial manufacturing processes. Finally, we present a model for enhancing the applicability of fuel cell-based power generation systems to assist in the realization of the H₂ economy as the best practice for enabling distributed energy. Overall, this study highlights the potential of SOFCs to make significant progress toward a sustainable and efficient energy future.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.335-343
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• 2019

In this study, $Sr_2Ni_{1.8}Mo_{0.2}O_{6-{\delta}}$ (SNM) with a double perovskite structure was investigated as an alternative anode for use in the $CH_4$ fuel in solid oxide fuel cells. SNM demonstrates a double perovskite phase over $600^{\circ}C$ and marginal crystallization at higher temperatures. The Ni nanoparticles were exsolved from the SNM anode during the fabrication process. As the SNM anode demonstrates poor electrochemical and electro-catalytic properties in the $H_2$ and $CH_4$ fuels, it was modified by applying a samarium-doped ceria (SDC) coating on its surface to improve the cell performance. As a result of this SDC modification, the cell performance improved from $39.4mW/cm^2$ to $117.7mW/cm^2$ in $H_2$ and from $15.9mW/cm^2$ to $66.6mW/cm^2$ in $CH_4$ at $850^{\circ}C$. The mixed ionic and electronic conductive property of the SDC provided electrochemical oxidation sites that are beyond the triple boundary phase sites in the SNM anode. In addition, the carbon deposition on the SDC thin layer was minimized due to the SDC's excellent oxygen ion conductivity.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.187-195
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• 2018

$Sr_{0.92}Y_{0.08}Ti_{1-x}Ni_xO_{3-{\delta}}$ (SYTN) was investigated in the presence of $H_2S$ containing fuels to assess the feasibility of employing oxide materials as alternative anodes. Aliovalent substitution of $Ni^{2+}$ into $Ti^{4+}$ increased the ionic conductivity of perovskite, leading to improved electrochemical performance of the SYTN anode. The maximum power densities were 32.4 and $45.3mW/cm^2$ in $H_2$ at $900^{\circ}C$ for the SYT anode and the SYTN anode, respectively. However, the maximum power densities in 300 ppm of $H_2S$ decreased by 7% and by 46% in the SYT and the SYTN anodes, respectively. To enhance the sulfur tolerance and to improve the electrochemical properties, the surface of SYTN anode was modified with samarium doped ceria (SDC) using the sol-gel coating method. For the SDC-modified SYTN anode, the cell performance was mostly recovered in the pure $H_2$ condition after 500-ppm $H_2S$ exposure in contrast to the irreversible cell performance degradation exhibited in the unmodified SYTN anode.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.129-132
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• 2007

Advanced structure of metal-supported solid oxide fuel cells was devised to overcome sealing problem and mechanical instability in ceramic-supported solid oxide fuel cells. STS430 whose dimensions were 26mm diameter, 1mm thickness and 0.4mm channel width was used as metal support. Thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support by using a cermet adhesive. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_{3}$ perovskite oxide was used as cathode material. It was noted that oxygen reduction reaction of cathode governed the overall cell performance from oxygen partial pressure dependance.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.161-165
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• 2021

In general, SOFCs mainly use Ni-YSZ cermet, a mixture of Ni and YSZ, as an anode material, which is stable in a high-temperature reducing atmosphere. However, when SOFCs have operated at a high temperature for a long time, the structural change of Ni occurs and it results in the problem of reducing durability and efficiency. Accordingly, a development of a new anode material that can replace existing nickel and exhibits similar performance is in progress. In this study, SrTiO₃, which is a perovskite-based mixed conductor and one of the candidate materials, was used. In order to increase the electrical conduction properties, Y_0.08Sr_0.92Fe_0.3Ti_0.7O₃, doped with 0.08 mol of Y³⁺ in Sr-site and 0.03 mol of transition metal Fe³⁺ in Ti-site, was synthesized and its chemical diffusion coefficient and reaction constant were measured. Its electrical conductivity changes were also observed while changing the oxygen partial pressure at a constant temperature. The performance as a candidate electrode material was verified by predicting the defect area through the electrical conductivity pattern according to the oxygen partial pressure.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.997-1001
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• 2016

Conductive ceramics are being developed to replace current Pt anodes in the electrolytic reduction of spent oxide fuels in pyroprocessing. While several conductive ceramics have shown promising electrochemical properties in small-scale experiments, their long-term stabilities have not yet been investigated. In this study, the chemical stability of conductive $La_{0.33}Sr_{0.67}MnO_3$ in $LiCl-Li_2O$ molten salt at $650^{\circ}C$ was investigated to examine its feasibility as an anode material. Dissolution of Sr at the anode surface led to structural collapse, thereby indicating that the lifetime of the $La_{0.33}Sr_{0.67}MnO_3$ anode is limited. The dissolution rate of Sr is likely to be influenced by the local environment around Sr in the perovskite framework.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.62-72
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• 2010

Solid oxide fuel cells(SOFCs) directly convert the fuel gases to electric energy through electrochemical reactions. The advantage of SOFCs is that they easily operate with diversified fuels such as natural gases owing to their high temperature operation. However, high temperature operation also incurs the challenge in enhancing long term reliability and durability of SOFCs. The most commonly used anode material is Ni/YSZ. This has, however, some drawbacks in terms of long-term reliability at high temperatures, hydrocarbon fuel usages, and so on, therefore the need to develop the new anode materials increases. This article summarizes the trend of the novel anode materials development of SOFCs.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.187-190
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• 2009

$LaCrO_3$ series are the most common candidate materials for a ceramic interconnect for SOFC and the thermal expansion coefficient of these matches very well with that of YSZ electrolyte. In this study, characteristics of the coated films on the anode-support, which were formed by using $La_{0.8}Ca_{0.2}CrO_3$, $La_{0.8}Sr_{0.2}CrO_3$, $La_{0.8}Ca_{0.2}Co_{0.1}Cr_{0.9}O_3$ for ceramic interconnet for SOFC, were investigated. All powders showed single perovskite phase and the precursors had spherical shapes of $2{\mu}m{\sim}30{\mu}m$. According to SEM analysis, coated film of LCC on pretreated anode-support was more thicker, whereas the coated film on untreated anode-support was densely formed. As the results of electrical conductivity of anode-support coated with the ceramic interconnects, LCCC exhibited the most excellent electrical conductivity of 0.15S/cm at $750^{\circ}C$.