• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.599-608
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• 2011

The Ni-Al anodes of the molten carbonate fuel cell (MCFC) with three different structures were successfully fabricated in order to reduce the thickness of the anode down to 0.3 mm; one was the non-supported anode made by a conventional tape casting method, and others were the supported anodes made by lamination or direct casting on the nickel screen. It was seen from the physical analyses and cell operation that the supported thin anodes made by direct casting showed good mechanical strength and cell performance because of a good contact between the anode materials and the support. The single cell using the above anode showed the cell voltage of 0.858 V at the current density of 150$mA/cm^2$ with the nitrogen cross-over of only 0.6% at the operation time of 1,000 h, which was similar to the performance of the conventional thick (0.7 mm) anode. The ability to utilize a thin configuration of anode should cut down the amount of nickel alloy and consequently reduce its manufacturing cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.207-214
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• 2009

Crossover of nitrogen from cathode to anode is inevitable in typical membranes used in PEM fuel cells. This crossovered nitrogen normally accumulates in the hydrogen recirculation system at anode side channels. Excessive buildup of nitrogen in the anode side lowers the relative hydrogen concentration and finally affects the performance of fuel cell stack. So it is very important to analysis the nitrogen gas crossover at various operating conditions. In this study, characterization of nitrogen gas crossover in PEM fuel cell stack was investigated. The mass spectroscopy (MS) has been applied to measure the amount of the crossovered nitrogen gas at the anode exit. Results show that nitrogen gas crossover rate was affected by current density, anode and cathode stoichiometric ratio and operating pressure. Current density, anode stoichiometric ratio and anode operating pressure do not affect nitrogen crossover rate but anode exit concentration of nitrogen. Cathode pressure and stoichiometric ratio largely affect the nitrogen crossover rate.

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.33-40
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• 2016

Sr_0.92Y_0.08TiO_3-δ (SYT) was investigated as an alternative anode in humidified CH₄ fuel for SOFCs at low temperatures (650 ℃-750 ℃) and compared with the conventional Ni/yttria-stabilized zirconia (Ni/YSZ) anode. The goal of the study was to directly use a hydrocarbon fuel in a SOFC without a reforming process. The cell performance of the SYT anode was relatively low compared with that of the Ni/YSZ anode because of the poor electrochemical catalytic activity of SYT. In the presence of CH₄ fuel, however, the cell performance with the SYT anode decreased by 20%, in contrast to the 58% decrease in the case of the Ni/YSZ anode. The severe degradation of cell performance observed with the Ni/YSZ anode was caused by carbon deposition that resulted from methane thermal cracking. Carbon was much less detected in the SYT anode due to the catalytic oxidation. Otherwise, a significant amount of bulk carbon was detected in the Ni/YSZ anode.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.646-652
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• 2022

The dead-end anode (DEA) system is a method that closes the anode outlet and supplies fuel by pressure. The DEA method could improve fuel usage and power efficiency through system simplification. However, flooding occurs due to water and nitrogen back diffusion from the cathode to the anode during the DEA operation. Flooding is a cause of decreased fuel cell performance and electrode degradation. Therefore, tthe structure and components of polymer electrolyte membrane fuel cell (PEMFC) should be optimized to prevent anode flooding during DEA operation. In this study, the effect of a porous flow field with metal foam on fuel cell performance and fuel efficiency improvement was investigated in the DEA system. As a result, fuel cell performance and purge interval were improved by effective water management with a porous flow field at the cathode, and it was confirmed that cathode flow field structure affects water back-diffusion. On the other hand, the effect of the porous flow field at the anode on fuel cell performance was insignificant. Purge interval was affected by metal foam properties and shown stable performance with large cell size metal foam in the DEA system.

• New & Renewable Energy
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• v.5 no.1
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• pp.11-17
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• 2009

To improve the performance of the anode-supported Solid Oxide Fuel Cell (SOFC) which can be operated at an intermediate temperature, the functional layer (FL) is introduced on a anode substrate. And the scandia-stabilized zirconia (ScSZ) and samaria-doped ceria (SDC) which have higher ionic conductivity and better chemical stability than yttria-stabilized zirconia (YSZ) are used as material for the anode FL with the Ni, The fabrication process of anode-supported single cell with the anode FL was established and the power density of those was evaluated. As a result, the sample with anode FL (Ni-YSZ) has higher power density than normal cell. The single cell which was composed of the FL (Ni-YSZ) and electrolyte (YSZ) showed about $550mW/cm^2$ of the maximum power density at $650^{\circ}C$ and $1430mW/cm^2$ at $750^{\circ}C$ respectively, In case of the single cell using the ScSZ and SDC as anode FL, the performance of samples decreased rapidly and those showed unstable voltage during long-term test. In case of using methane as a fuel, the cell performance with each FL decreased comparing with $H_2$ fuel. In the region of a high current density, there are large concentration polarizations.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.82-89
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• 2006

The redox behaviors of anode-supported flat tube for solid oxide fuel cell has been studied. The mass change of the extruded NiO/YSZ anode flat tube during redox cycling was examined by thermogravimetric analysis(TGA). The result of TGA was shown a rapidly mass change in the range of $455\;-\;670^{\circ}C$ and the reoxidation of the NiO/YSZ anode was almost completed at $750^{\circ}C$. The starting temperature of reoxidation and the maximum temperature of oxidation rate decreased with increasing the reoxidation cycle, which is attributed to the increased porosity caused by volume change. Bending strengths of the NiO/YSZ anode after redox cycling were 96 - 80 MPa and the bending strength decreased slightly with increasing the redox cycle. On the other hand, the bending strength of the NiO/YSZ anode with electrolyte showed 130 MPa after first redox cycling but decreased rapidly with increasing the redox cycle. From the results of the bending test and the microstructure observation, we conclude that the crack initiation of the electrolyte-coated NiO/YSZ anode was induced easily at interface of electrolyte/anode tube and propagated cross the electrolyte.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.691-695
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• 2002

A low temperature anode-supported tubular solid oxide fuel cell was developed. The anode-supported tube was fabricated using extrusion process. Then the electrolyte layer and the cathode layer were coated onto the anode tube by slurry dipping process, subsequently. The anode tube and electrolyte were co-fired at $140^{\circ}C$, and the cathode was sintered at $1200^{\circ}C$. The thickness and gas permeability of the electrolyte depended on the number of coating and the slurry concentration. Anode-supported tube was satisfied with SOFC requirements, related to electrical conductivity, pore structure, and gas diffusion limitations. At operating temperature of $800^{\circ}C$, open circuit voltage of the cell with gastight and dense electrolyte layer was 1.1 V and the cell showed a good performance of 450 mW/$\textrm{cm}^2$.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.480-486
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• 2013

In this study, tubular SOFC unit cell with advanced anode current collector was fabricated to improve the cell performance. First, we prepared two types of single cells having the same manufacture processes such as the same electrolyte, electrode coating condition and sintering processes. And then to compare the developed single cell performance with conventional cells, we changed the anode current collecting methods. From the impedance analysis and I-V curve analysis, the cell performance of advanced cell is much higher than that of conventional cell.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.526-532
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• 2010

The anode may inevitably undergo a number of reduction.oxidation (redox) cycles during solid oxide fuel cells (SOFCs) operation. The re-oxidation of Ni to NiO causes significant mechanical stress to be developed across the anode, which may destroy the integrity of the whole cell. In this study, the redox behavior of Ni-YSZ composite was examined at $800^{\circ}C$ using various characterization techniques.