• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.501-506
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• 2019

To overcome the limitations of the conventional Ni anode-supported SOFCs, various types of ceramic anodes have been studied. However, these ceramic anodes are difficult to commercialize because of their low cell performances and difficulty in manufacturing anode-support typed SOFCs. Therefore, in this study, to use these ceramic anodes and take advantage of anode-supported SOFC, which can minimize ohmic loss from the thin electrolyte, we fabricated cathode support-typed SOFC. The cathode-support of LSCF-YSZ was prepared by the acid treatment of conventional Ni-YSZ (Yttria-stabilized Zirconia) anode-support, followed by the infiltration of LSCF to YSZ scaffold. The composite of $La(Sr)Ti(Ni)O_3$ and $Ce(Mn,Fe)O_2$ was used as the ceramic anode. The fabricated cathode-supported button cell showed a relatively low power density of $0.207Wcm^{-2}$ at $850^{\circ}C$; however, it is expected to show better performance through the optimization of the infiltration rate and thickness of LSCF-YSZ cathode-support layer.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.235-242
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• 2011

This perspective describes recent advances made in the development of various electrochemical technologies to treat waste water containing organic pollutants, reducible/oxidizable and non-reducible/non-oxidizable anions and cations using redox reactions on the solid surface as well as at the interface between solid electrode and liquid electrolyte. Some of representative multiplexing and hybrid electrochemical treatment technologies are discussed, which have great advantages of high efficiency, stability and cost-effective instrumentation without the need of considering non-specific conditions such as high-temperature and high-pressure; however, choices and usages of electrode materials are absolutely critical issues.

• Journal of Electrochemical Science and Technology
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• v.12 no.2
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• pp.246-256
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• 2021

Mo,Cu-doped CeO₂ (CMCuO) nanopowders were synthesized by the nitrate-fuel combustion method aiming to improve the electrical and electrochemical properties of its Mo-doped CeO₂ (CMO) parent by the addition of copper. An electrical conductivity of ca. 1.22·10^-2 S cm^-1 was measured in air at 800℃ for CMCuO, which is nearly 10 times higher than that reported for CMO. This increase was associated with the inclusion of copper into the crystal lattice of ceria and the presence of Cu and Cu₂O as secondary phases in the CMCuO structure, which also could explain the increase in the charge transfer activities of the CMCuO based anode for the hydrogen and carbon monoxide electro-oxidation processes compared to the CMO based anode. A maximum power density of ca. 120 mW cm^-2 was measured using a CMCuO based anode in a solid oxide fuel cell (SOFC) with YSZ electrolyte and LSM-YSZ cathode operating at 800℃ with humidified syngas as fuel, which is comparable to the power output reported for other SOFCs with anodes containing copper. An increase in the area specific resistance of the SOFC was observed after ca. 10 hours of operation under cycling open circuit voltage and polarization conditions, which was attributed to the anode delamination caused by the reduction of the Cu₂O secondary phase contained in its microstructure. Therefore, the addition of a more electroactive phase for hydrogen oxidation is suggested to confer long-term stability to the CMCuO based anode.

• Journal of the Korean institute of surface engineering
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• v.42 no.5
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• pp.227-231
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• 2009

The niobium capacitor showed somewhat more unstable characteristics than the commercial tantalum capacitors, but is nonetheless considered applicable as a future substitute for tantalum capacitors. In this study, niobium powder was fabricated by metallothermic reduction process using $K_2NbF_7$ as the raw materials, KCl and KF as the diluents and Na as the reducing agent. The niobium particle size greatly decreased from 0.7um to 0.2 um as the amount of diluent increased. However if a higher surface area of powder is required, more diluents need to be used in the said method in order to produce niobium powder. The niobium powder morphology and particle size are very sensitive to a amount of sodium excess. The particle size of niobium powder increased with a increasing amount of sodium excess. When more diluent and sodium are used, the niobium powder will be contaminated with more impurities such as Fe, Cr, Ni so on.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.319-325
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• 2011

The electrical properties of sputtered GDC thin films on $Al_2O_3$ substrates was studied. The electrical properties of the films were measured to evaluate the ion conductivity of GDC thin films for co-planar SOFC electrolytes. The impedance of the GDC thin films on $Al_2O_3$ substrates was affected by the film thickness and the impedance of thin film exhibited higher value than thick films. Similarly, the conductivity of the thick film showed much higher value than thin films. It indicated that the film thickness is the main factor affecting the conductivity and impedance of the GDC electrolyte for the co-planar SOFC.

• Advances in materials Research
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• v.2 no.1
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• pp.37-49
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• 2013

The transition metal salt doped solid polymer electrolyte [TSPE] were prepared with HPMC as a host polymer. The virgin and doped films were prepared by solution-casting method and investigated using wide angle X-ray scattering method. Micro structural parameters like lattice strain (g%), stacking/twin faults, the average number of unit cells counted in a direction perpendicular to the Bragg's plane (hkl) spacing of (hkl) planes dhkl, crystallite size Ds, distortion width, standard deviation were determined by whole pattern powder fitting (WPPF) method, which is an extension of single order method. It is found that the crystallite size decreases with the increase in the content of $FeCl_3$. This decrease is due to increase in localized breaking of polymer network which also accounts for the amorphous nature of the material. The filler inorganic salt $FeCl_3$ acts as plasticizer. FTIR study also confirms and justifies the interaction between the polymer and in-organic salt in the matrix. Physical properties like mechanical stability and Ac conductivity in these films are in conformity with the X-ray results.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1465-1468
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• 2014

In this study, an intermediate temperature ionic conductor, $Ce_{0.95}Eu_{0.05}P_2O_7$, was prepared by solid state reaction. The variation of conductivities with the pressure $pH_2O$ or time were studied. The highest conductivity of $Ce_{0.95}Eu_{0.05}P_2O_7$ sample was observed in dry air atmosphere at $300^{\circ}C$ to be $1.1{\times}10^{-4}S{\cdot}cm^{-1}$ and in wet air atmosphere ($pH_2O=7.4{\times}10^3Pa$) at $100^{\circ}C$ to be $1.4{\times}10^{-3}S{\cdot}cm^{-1}$, respectively. The log ${\sigma}$ ~ log ($pO_2$) plot result indicated that $Ce_{0.95}Eu_{0.05}P_2O_7$ was almost a pure ionic conductor under high oxygen partial pressure and a mixed conductor of ion and electron under low oxygen partial pressure.

• Korean Journal of Materials Research
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• v.16 no.3
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• pp.193-197
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• 2006

The sodium/sulfur(Na/S) battery has many advantages such as high theoretical specific energy(760Wh/kg), and low material cost based on the abundance of electrode material in the earth. It has been reported that the electrochemical properties of sodium/sulfur cell above $300^{\circ}C$, utilized a solid ceramic electrolyte and liquid sodium and sulfur electrodes. A lot of researches have been performed in this field. Recently, Na/S battery system was applied for electricity storage system for load-leveling. One of severe problems of sodium/sulfur battery was high operating temperature above $300^{\circ}C$, which could induce the explosion and corrosion by molten sodium, sulfur and polysulfides. In order to develop sodium battery operated at low temperature, sodium ion battery has been studied using carbon anode, and sodium oxides cathodes. However, the energy densities of the sodium ion batteries were much lower than high temperature sodium/sulfur cell. In this study, the sodium/sulfur battery with 1M $NaCF_3SO_3$ is tested at room temperature. The charge-discharge mechanism was discussed based on XRD, DSC, SEM and EDS results.

• Transactions on Electrical and Electronic Materials
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• v.15 no.2
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• pp.96-99
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• 2014

We fabricated $(Li_{0.5-x}Na_xLa_{0.5})Ti_{0.8}Zr_{0.2}O_3$(LNTLZ)ceramics ($0{\leq}x{\leq}0.4$) with a perovskite structure via standard solid state synthesis. The influence of Na content on the structural and electrical properties of LNTLZ ceramics was also investigated. During XRD patterns analysis, all of the samples showed orthorhombic structure. The resistance of LNTLZ ceramics decreased as Na content increased, and the maximum activation energy shows 0.56 eV at x=0.4 at room temperature. These results indicated that LNTLZ ceramics are a candidate for use Lithium ion batteries as electrolytes.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.282-285
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• 2009

This study presents preparation and characterization of composite membranes based on ionic liquids. The ionic liquids act as water in sulfonated membranes. On the behalf of ionic conduction through ionic liquid inside the membranes, non-aqueous membranes showed Arrenhius dependence on temperature with no external humidification. It was implied that hopping mechanism of proton was dominant in the ionic liquid based membranes. In addition, small angle X-ray (SAXS) studies provided the information on morphology of ionic clusters formed by the interaction between sulfonic acid groups of the polymers and ionic liquids. The SAXS spectra showed matrix peaks, ionomer peaks and Prodo's law for Nafion based composite membranes and only matrix peaks for hydrocarbon based ones. However, ionic conductivity and atomic force microscopy (AFM) images showed the clear formation of ionic clusters of the hydrocarbon based composite membranes. It implies for ionic liquid based high temperature membranes that it is important to use sulfonated polymers as solid matrix of ionic liquid which can form clear ionic clusters in SAXS spectra.