Hae-Jin Hwang

Fabrication and Cell Properties of Flattened Tube Segmented-in-Series Solid Oxide Fuel Cell-Stack Using Decalcomania Paper

In the segmented-in-series solid-oxide fuel cells (SIS-SOFCs), fabrication techniques which use decalcomania paper have many advantages, i.e., an increased active area of the electrode; better interfacial adhesion property between the anode, electrolyte and cathode; and improved layer thickness uniformity. In this work, a cell-stack was fabricated on porous ceramic flattened tube supports using decalcomania paper, which consists of an anode, electrolyte, and a cathode. The anode layer was 40 µm thick, and was porous. The electrolyte layers exhibited a uniform thickness of about 20 µm with a dense structure. Interfacial adhesion was improved due to the dense structure. The cathode layers was 30 µm thick with porous structure, good adhesion to the electrolyte. The ohmic resistance levels at 800, 750 and 700 o C were measured, showing values of 1.49, 1.58 and 1.65 Ω·cm 2 , respectively. The polarization resistances at 800, 750 and 700 o C were measured to be 1.63, 2.61 and 4.17 cm 2 , respectively. These lower resistance values originated from the excellent interfacial adhesion between the anode, electrolyte and cathode. In a two-cell-stack SOFC, open-circuit voltages(OCVs) of 1.915, 1.942 and 1.957 V and maximum power densities(MPD) of 289.9, 276.1 and 220.4 mW/cm 2 were measured at 800, 750 and 700 o C, respectively. The proposed fabrication technique using decalcomania paper was shown to be feasible for the easy fabrication of segmented-in-series flattened tube SOFCs.

SnO₂-(1-x)P₂O₅ -xB₂O₃ 유리의 열적, 구조적 특성

SnO₂-(1-x)P₂O? -xB₂O₃ glass system were prepared by melt-quenching technique in the compositional series containing 50, 55 and 60 ㏖% of SnO₂. Local structure of the glasses was investigated by Raman and FT-IR measurements. A large glass-forming region was found at the phosphate side of the ternary system with homogeneous glasses containing up to 5~25 ㏖% of B₂O₃. According as content of B₂O₃ increases, theraml expansion coefficient of glass decreased but transition temperature and softening temperature increased. Because these phenomenon changed local structure of glass. According as content of B₂O₃ increases, quantity of bridging oxygen increased. Also, according as content of SnO₂ increases, confirmed that quantity of non-bridging oxygen increases.

Effect of Bi and Zr addition on yellow colour properties of environment-friendly ceria-based pigments

Inorganic pigments have been received a great attention for various applications including paint, glazed ceramic ink, art tile, and building exterior due to their excellent thermal and chemical stability. Traditionally, the compositions of , CdS and CdSe have been widely used as a yellow inorganic pigment. However, the use of these compositions has been restricted in recent years, because they contain harmful elements such as Cd, Cr, Pb and Se. In this study, new environment-friendly ceria-based pigment was synthesized using solid state reaction. Crystal structure and morphology of the obtained yellow pigment were analyzed using XRD and SEM, respectively. Substitutional effect of Zr and Bi on the pigment color was analyzed using UV-vis. spectrophotometer and CIE analysis. The crystal structure of the obtained pigments was dependent on the calcination temperature. The color characteristics and absorption band of the pigments were dependent on the calcination temperature and Zr, Bi contents. As a result, all the obtained yellow pigments showed the effective absorption ranged from ultraviolet to visible light, and (x

Electrochemical Performance of a Nd2-xSrxNiO4+δ/GDC(x = 0, 0.4, 0.6) as a SOFC Cathode Material

ABSTRACT Mixed ionic and electronic conducting K 2 NiF 4 -type oxide, Nd 2-x Sr x NiO 4+δ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a Nd 2-x Sr x NiO 4+δ -GDC cathode, a Ni-YSZ anode and 8YSZ as anelectrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties wasexamined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (δ)decreased. Sr doping into Nd 2 NiO 4+δ resulted in an increase in the cathode polarization resistance and an decrease in the power densityof the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the Nd 2-x Sr x NiO 4+δ cathode.Key words : Solid oxide fuel cells, Nd 2-x Sr x NiO 4+δ, Strontium, Electrical conductivity, Excess oxygen 1. 서 론고체산화물연료전지 (Solid Oxide Fuel Cells, SOFCs)는기존의 화력발전 또는 다른 형태의 연료전지에 비하여 고효율로 전기에너지를 생산할 수 있기 때문에 분산발전 또는 대규모 집중발전용 에너지 변환 장치로 주목받고 있다. 한편 SOFC를 이용하여 상용화 가능한 전류밀도를 얻기 위해서는 800

Synthesis and characterization of LiMn 1.5 Ni 0.5 O 4 powders using polymerization complex method

The , substituting a part of Mn with Ni in the , the spinel structure has good charge-discharge cycle stability and high discharge capacity at 4.7 V. In this study powders were synthesized by polymerization complex method. The effect on the characteristics of synthesized powders was studied with citric acid (CA) : metal ion (ME) molar ratio (5 : 1, 10 : 1, 15 : 1, 30 : 1) and calcination temperature (). Single phase of was observed from XRD analysis on the powders calcined at low () and high temperatures (). The crystalline size and crystallinity increased with calcination temperature. At low calcination temperature the particle size decreased and specific surface area increased as the CA molar ratio increased. On the other hand, high particle growth rate at high calcination temperature interfered the particle size reduction and specific surface area increase induced by the increase of CA molar ratio.

Characterization and synthesis of aqueous pink-red ceramic ink for digital inkjet printing

Ceramic ink-jet printing technology in art tiles, decorated tablewares and other porcelain products has many advantages of fast and precision printing of various images with high efficiency and low cost. For the application to ink-jet printing, ceramic ink requires a stable dispersibility with nano-sized pigments. In this paper, characteristics of pink-red aqueous ceramic ink for ink-jet printing was demonstrated. CaCr0.1Sn0.8SiO5 pigment was synthesized using solid state reaction and deagglomerated using attrition milling. The aqueous ceramic ink contains 10 wt% of the obtained CaCr0.1Sn0.8SiO5 nanopigment with 0.4 wt% of sodium dodecyl sulfate (SDS) as a dispersion agent. Viscosity of CaCr0.1Sn0.8SiO5 aqueous ceramic ink was adjusted using 0.18 wt% of polyvinyl alcohol (PVA) for a suitable jetting from the nozzle. The prepared pink-red ceramic ink showed a good jetting property with formation of a single sphere-shaped droplet after 180 μs without a tail and satellite droplet.

Fabrication of a Microtubular La0.6Sr0.4Ti0.2Fe0.8O3−δ Membrane by Electrophoretic Deposition for Hydrogen Production

Microtubular type La0.6Sr0.4Ti0.2Fe0.8O3−δ (LSTF) membranes were prepared by electrophoretic deposition (EPD). The oxygen permeation and hydrogen production behavior of the membranes were investigated under various conditions. LSTF green layer was successfully coated onto a carbon rod and, after heat treatment at 1400°C in air, a dense LSTF tubular membrane with a thickness of 250u2009mm can be obtained. The oxygen permeation and hydrogen production rate were enhanced by CH4 in the permeate side, and the hydrogen production rate by water splitting was 0.22u2009mL/min·cm2 at 1000°C. It is believed that hydrogen production via water splitting using these tubular LSTF membranes is possible.

Power Densities According to Anode Functional Layers on the Manufactured SOFC Unit Cells Using Decalcomania Method

The properties of SOFC unit cells manufactured using the decalcomania method were investigated. SOFC unit cell manufacturing using the decalcomania method is a very simple process. In order to minimize the ohmic loss of flattened tube type anode supports of solid oxide fuel cells(SOFC), the cells were fabricated by producing an anode function layer, YSZ electrolyte, LSM electrode, etc., on the supports and laminating them. The influence of these materials on the power output characteristics was studied when laminating the components and laminating the anode function layer between the anode and the electrolyte to improve the output characteristics. Regarding the performance of the SOFC unit cell, the output was 246 at a temperature of in the case of not laminating the anode function layer; however, this value was improved by a factor of two to 574 due to the decrease of the ohmic resistance and polarization resistance of the cell in the case of laminating the anode function layer. The outputs appeared to be as high as 574 and 246 at a temperature of in the case of using decalcomania paper when laminating the electrolyte layer using the in dip-coating method; however, the reason for this is that interfacial adhesion was improved due to the dense structure, which leads to a thin thickness of the electrolyte layer.

The Effect of Acid Treatment Time for Ni Plating on the Joint of α-Al 2 O 3 and Ni Metal

>> In Na-base Battery for ESS, α-Al2O3 and metal bonding was used to prevent direct reaction between electrolyte and electrode. The hard metal was metalized at 1600°C in a flowing hydrogen gas for high bonding strength. In this study, instead of hard metal metalizing, Ni was plated on α-Al2O3 by electroless Ni plating technique and then bonded with metal. To enhance the bonding strength, surface of α-Al2O3 was treated with H3PO4. The effects of strength and leakage of joining as a function of acid treatment time on α-Al2O3 are described.

Electrochemical Performance of a Nd 2-x Sr x NiO 4+ δ /GDC(x

ABSTRACT Mixed ionic and electronic conducting K 2 NiF 4 -type oxide, Nd 2-x Sr x NiO 4+δ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a Nd 2-x Sr x NiO 4+δ -GDC cathode, a Ni-YSZ anode and 8YSZ as anelectrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties wasexamined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (δ)decreased. Sr doping into Nd 2 NiO 4+δ resulted in an increase in the cathode polarization resistance and an decrease in the power densityof the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the Nd 2-x Sr x NiO 4+δ cathode.Key words : Solid oxide fuel cells, Nd 2-x Sr x NiO 4+δ, Strontium, Electrical conductivity, Excess oxygen 1. 서 론고체산화물연료전지 (Solid Oxide Fuel Cells, SOFCs)는기존의 화력발전 또는 다른 형태의 연료전지에 비하여 고효율로 전기에너지를 생산할 수 있기 때문에 분산발전 또는 대규모 집중발전용 에너지 변환 장치로 주목받고 있다. 한편 SOFC를 이용하여 상용화 가능한 전류밀도를 얻기 위해서는 800