• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.773-776
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• 2009

In this paper, new concept of the diesel fuel processing is introduced for the stable operation of solid oxide fuel cells (SOFCs). Heavier hydrocarbons than $CH_4$, such as ethylene, ethane, propane, and etc., induce the carbon deposition on anode of SOFCs. In the reformate of heavy hydrocarbons (diesel, gasoline, kerosene, and JP-8), concentration of ethylene is usually higher than low hydrocarbons such as ethane, propane, and butane. So, removal of low hydrocarbons (over C1-hydrocarbons), especially ethylene, at the reformate gases is important for stable operation of SOFCs. New methodology as named "post-reformer" is introduced for removing the low hydrocarbons at the reformate gas stream. Catalyst of the NECS-PR4 is selected for post-reforming catalyst because the catalyst of NECS-PR4 shows the high selectivity for removing low hydrocarbons and achieving the high reforming efficiency. The diesel reformer and post-reformer are continuously operated for about 200 hours as integrated mode. The reforming performance is not degraded and low hydrocarbons in the diesel reformate are completely removed.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.224-230
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• 2014

Nano-sized gadolinium-doped ceria (GDC)/nickel particle-dispersed $La_ySr_{1-y}Ti_{1-x}Fe_xO_3$ (LSFTO)-based composite solid oxide fuel cell anodes were fabricated by an infiltration method and the effects of the GDC/Ni nanoparticles on the anode polarization resistance and cell performance were investigated in terms of the infiltration time and nickel content. The anodic polarization resistance of the LSFTO anode was significantly enhanced by GDC and/or Ni infiltration and it decreased with increasing infiltration time and Ni content, respectively. It is believed that the observed phenomena are associated with enhancement of the ionic conductivity and catalytic activity in the nanocomposite anodes by the addition of GDC and Ni. Power densities of cells with the LSFTO and LSFTO-GDC/Ni nanocomposite anodes were 150 and $300mW/cm^2$ at $800^{\circ}C$, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.84.1-84.1
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• 2011

Typical solid oxide fuel cells (SOFCs) have limited applications because they operate at high temperature due to low ionic conductivity of electrolyte. Thin film solid oxide fuel cell with yttria stabilized zirconia (YSZ) electrolyte is developed to decrease operating temperature. Pt/YSZ/Pt thin film SOFC was fabricated on anodic aluminum oxide (AAO). The crystalline structure of YSZ electrolyte by sputter is heavily depends on the roughness of porous Pt layer, which results in pinholes. To deposit YSZ electrolyte without pinholes and electrical shortage, it is necessary to deposit smoother and denser layer between Pt anode layer and YSZ layer by sputter. Atomic Layer Deposition (ALD) technique is used to deposit pre-YSZ layer, and it improved electrolyte quality. 300nm thick Bi-layered YSZ electrolyte was successfully deposited without electrical shortage.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.402.1-402.1
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• 2016

The performance of solid oxide fuel cells (SOFCs) is directly related to the electrocatalytic activity of composite electrodes in which triple phase boundaries (TPBs) of metallic catalyst, oxygen ion conducting support, and gas should be three-dimensionally maximized. The distribution morphology of catalytic nanoparticle dispersed on external surfaces is of key importance for maximized TPBs. Herein in situ grown nickel nanoparticle onto the surface of fluorite oxide is demonstrated employing gadolium-nickel co-doped ceria ($Gd0.2-xNixCe0.8O2-{\delta}$, GNDC) by reductive annealing. GNDC powders were synthesized via a Pechini-type sol-gel process while maximum doping ratio of Ni into the cerium oxide was defined by X-ray diffraction. Subsequently, NiO-GNDC composite were screen printed on the both sides of yttrium-stabilized zirconia (YSZ) pellet to fabricate the symmetrical half cells. Electrochemical impedance spectroscopy (EIS) showed that the polarization resistance was decreased when it was compared to conventional Ni-GDC anode and this effect became greater at lower temperature. Ex situ microstructural analysis using scanning electron microscopy after the reductive annealing exhibited the exsolution of Ni nanoparticles on the fluorite phases. The influence of Ni contents in GNDC on polarization characteristics of anodes were examined by EIS under H2/H2O atmosphere. Finally, the addition of optimized GNDC into the anode functional layer (AFL) dramatically enhanced cell performance of anode-supported coin cells.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.163-167
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• 2013

A modified two-point impedance spectroscopy technique exploits the geometric constriction between an electrolyte and a cathode with an emphasis on semispherical-shaped electrolytes. The spatial limitation in the electrolyte/electrode interface leads to local amplification of the electrochemical reaction occurring in the corresponding electrolyte/electrode region. The modified impedance spectroscopy was applied to electrical monitoring of a YSZ ($Y_2O_3$-stabilized $ZrO_2$)/SSC ($Sm_{0.5}Sr_{0.5}CoO_3$) system. The resolved bulk and interfacial component was numerically analyzed in combination with an equivalent circuit model. The effectiveness of the "spreading resistance" concept is validated by analysis of the electrode polarization in the cathode materials of solid oxide fuel cells.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.469-477
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• 2016

The application of nanomaterials for electrodes of intermediate temperature solid oxide fuel cells (SOFC) is introduced. In conventional SOFCs, the operating temperature is higher than 1073 K, and so application of nanomaterials is not suitable because of the high degradation rate that results from sintering, aggregation, or reactions. However, by allowing a decrease of the operating temperature, nanomaterials are attracting much interest. In this review, nanocomposite films with columnar morphology, called double columnar or vertically aligned nanocomposites and prepared by pulsed laser ablation method, are introduced. For anodes, metal nano particles prepared by exsolution from perovskite lattice are also applied. By using dissolution and exsolution into and from the perovskite matrix, performed by changing $P_{O2}$ in the gas phase at each interval, recovery of the power density can be achieved by keeping the metal particle size small. Therefore, it is expected that the application of nanomaterials will become more popular in future SOFC development.

• 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.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.379-381
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• 2009

The simulation model for metal-supported Solid Oxide Fuel Cell(SOFC) is developed in this study. Open circuit voltage is calculated using Nernst equation and Gibbs free energy is required by thermodynamic. The exchange current densities are compared with experimental results since exchange current density is most effective factor for the activation loss. Liu's study is used for the exchange current density of cathode, BSCF, and Koide's result is applied for the exchange current density of anode, Ni/YSZ. For the ohmic loss, ionic conductivity of YSZ is described from Kilner's mode and the data are compared with Wanzenberg's experimental data. Diffusivity is an important factor for the mass transfer through the porous medium. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.373-380
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• 2001

Solid Oxide Fuel Cells (SOFCs) have received considerable attention because of the advantages of high effiiciency, low pollution, cogeneration application and excellent integration with simplified reformer In this paper, we reported development of anode-tubular SOFC by wet process. For making tubular cell, Ni-cermet YSZ anode tube was fabricated using extrusion process, and YSZ electrolyte layer and LSM-YSZ composite, LSM, LSCF cathode layer were coated onto the anode supported tube using slurry dipping process and sintered by co-firing process. By using this tubular cell, we fabricated single cell consisted of the various cathode layers and 4 cell stack with an effective area of $75 cm^2$ per single cell, and evaluated their performance characteristics.

• Ceramist
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• v.23 no.2
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• pp.132-144
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• 2020

Solid oxide fuel cell (SOFC) have attracted much attention due to clean, efficient and environmental-friendly generation of electricity for next-generation energy conversion devices. Recently, many studies have been reported on improving the performance of SOFC electrodes and electrolytes by applying atomic layer deposition (ALD) process, which has advantages of excellent film quality and conformality, and precise control of film thickness by utilizing its unique self-limiting surface reaction. ALD process with these advantages has been shown to provide functional ceramic interfaces for SOFC electrodes and electrolytes. In this article, recent examples of successful functionalization and stabilization on SOFC electrodes and electrolytes by the application of ALD process for realizing high performance SOFC cells are reported.