• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.110-112
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• 2006

Membrane electrode assembly (MEA) for polymer electrolyte fuel cell (PEFC) are commonly prepared in the research laboratory by spraying, screen-printing and brushing catalyst slurry onto membrane or other support material like carbon paper or polyimide film in a batch style. These hand applications of the catalyst slurry are painstaking process with respect to precision of catalyst loading and reproducibility. It has been generally mentioned that the adoption of continuous process is very helpful to develop the reliable product. In the present work, we report the results of using continuous type coater with doctor-blade to coat catalyst slurry for preparing the MEA catalyst layers In a faster and highly reproducible fashion. We show that while expectedly faster than batch style, the machine coater requires the use of slurry of appropriate composition and a properly selected transfer decal material in order to achieve superior MEA plat lnw loading reproducibility. To make highly viscous catalyst slurry that is imperative for using coater, we use 40wt.% Nafion solution and minimize the content of organic solvent. And the choice of proper high surface area catalyst is important in the viewpoint of making well-dispersed slurry. After catalyst coating onto the support material, we transferred the catalyst layer to both sides of Nafion membrane by hot-pressing In this case, the degree of transfer was Influenced by hot-pressing condition including temperature, pressure, and time. To compare the transferring ability, we compared so many films and detaching papers. And among the support, polyethylene terephthalate(PET) film shows the prominent result.

• 한국수소및신에너지학회논문집
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• 제24권3호
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• pp.223-229
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• 2013

Polymer Electrolyte Membrane Fuel Cell (PEMFC) is a power generation system to convert chemical energy of fuels and oxidants to electricity directly by electrochemical reactions. As a catalyst support for PEMFCs, carbon black has been generally used due to its large surface area and high electrical conductivity. However, under certain circumstances (start up/shut down, fuel starvation, ice formation etc.), carbon supports are subjected to serve corrosion in the presence of water. Therefore, it would be desirable to switch carbon supports to corrosion-resistive support materials such as metal oxide. $TiO_2$ has been attractive as a support with its stability in fuel cell operation atmosphere, low cost, commercial availability, and the ease to control size and structure. However, low electrical conductivity of $TiO_2$ still inhibits its application to catalyst support for PEMFCs. In this paper, to explore feasibility of $TiO_2$ as a catalyst support for PEMFCs, $TiO_2$ nanofibers were synthesized by electrospinning and calcinated at 600, 700, 800 and $900^{\circ}C$. Effects of calcination temperature on crystal structure and electrical conductivity of electrospun $TiO_2$ nanofibers were examined. Electrical conductivity of $TiO_2$ nanofibers increased significantly with increasing calcination temperature from $600^{\circ}C$ to $700^{\circ}C$ and then increased gradually with increasing the calcination temperature from $700^{\circ}C$ to $900^{\circ}C$. It was revealed that the remarkable increase in electrical conductivity could be attributed to phase transition of $TiO_2$ nanofibers from anatase to rutile at the temperature range from $600^{\circ}C$ to $700^{\circ}C$.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.7-12
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• 2024

고분자 전해질 연료전지(PEMFC) 내구성에 촉매 지지체 내구성이 미치는 영향이 크다. 촉매 지지체의 가속 내구 평가는 높은 전압(1.0~1.5 V)에서 진행되어 촉매층의 촉매와 이오노머 바인더도 같이 열화되어 지지체 내구성 평가에 방해가 된다. 내구성 평가대상인 지지체가 더 열화되는 조건을 찾고자 기존의 프로토콜 (DOE 프로토콜)을 개선하였다. 상대습도를 35% 낮추고 전압변화 횟수를 감소시킨 프로토콜 (MDOE)을 개발하였다. 1.0 ↔ 1.5 V 전압변화 사이클 반복 후에 촉매 비활성도 (MA)와 전기화학적 활성면적 (ECSA), 전기이중층 용량 (DLC), Pt 용해와 입자 성장 등을 분석하였다. 비활성도 감소 40% 도달하는데 MDOE 프로토콜은 500 사이클 밖에 안되어 DOE방법보다 전압변화 횟수를 감소시키면서 카본 지지체 열화를 DOE 프로토콜보다 50% 증가시킬 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2222-2227
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• 2007

Newly structured metal-supported solid oxide fuel cell was fabricated and characterized by impedance analysis and galvanodynamic experiment. Using a cermet adhesive, thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support of which flow channel was fabricated. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_3$ perovskite oxide was used as cathode material. Single cell performance was increased and saturated at operating time to 300hours at 800$^{\circ}C$ because of cathode sintering effect. The sintering effect was reinvestigated by half cell test and exchange current density was measured as 0.005A/$cm^2$. Maximum power density of the cell was 0.09W/$cm^2$ at 800$^{\circ}C$. Numerical analysis was carried out to classify main factors influencing the single cell performances. Compared to experimental IV curve, simulated curve based on experimental parameters such as exchange current density was in good agreement.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.767-772
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• 2012

In support of optimizing electrorefining technology for treating spent nuclear fuel, lithium drawdown has been investigated for separating actinides from molten salt electrolyte. Drawdown reaction selectivity is a major issue that requires investigation, since the goal is to remove actinides while leaving the fission products and other components in the salt. A series of lithium drawdown tests with surrogate fission product chlorides was run to obtain selectivity data with non-radioactive salts, develop a predictive model, and draw conclusions about the viability of using this process with actinide-loaded salt. Results of tests with CsCl, $LaCl_3$, $CeCl_3$, and $NdCl_3$ are reported here. Equilibrium was typically achieved in less than 10 hours of contact between lithium metal and molten salt under well-stirred conditions. Maintaining low oxygen and water impurity concentrations (<10 ppm) in the atmosphere was observed to be critical to minimize side reactions and maintain stable salt compositions. An equilibrium model has been formulated and fit to the experimental data. Good fits to the data were achieved. Based on analysis and results obtained to date, it is concluded that clean separation between minor actinides and lanthanides will be difficult to achieve using lithium drawdown.

• 한국수소및신에너지학회논문집
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• 제24권6호
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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.

• 전기화학회지
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• 제6권3호
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• pp.183-186
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• 2003

In a PEM fuel cell electrode, backing layer has tremendous impact on electrode performance. The backing layer provides structural support for the porous electrode, distributes the reactants to the other layers and acts as a current collector. It has major influence on the water management in a PEM fuel cell. Selection of suitable backing layer material for the fabrication of electrode is thus very important to achieve high performance. In this paper we have compared the performance of PEM fuel cell electrodes fabricated using carbon paper EC-TPI-060T, carbon cloth EC-CCI-060T, (ElectroChem Inc.USA) and Carbon cloth from Textron, USA (CPW 003 grade). Mass transport problem was observed under non-pressurized condition, at high current densities, in the caie of EC-CC1-060T carbon cloth electrode (at $50^{\circ}C$), due to its higher thickness. The performance of carbon paper electrode was higher than EC-CCI-060T carbon cloth electrode. The performance of Textron carbon cloth was comparable to EC-TPI -060T carbon paper.

• 대한화학회지
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• 제57권5호
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• pp.574-590
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• 2013

A new solid complexes of Ti(IV), Y(III) and Ce(IV) have been synthesized with ofloxacin. The formulae and structure of the complexes have been proposed in the light of analytical, spectral ($^1H$ NMR, IR and UV-Visible), magnetic, molar conductivities and thermal studies. The complexes are soluble in DMSO-$d_6$ and DMF. The measured molar conductance values indicate that, the three complexes are electrolyte in nature. The results support the formation of the complexes and indicated that ofloxacin reacts as a bidentate ligand chelate to the metal ion through the pyridone oxygen and one carboxylato oxygen. The kinetic parameters of thermogravimetric and its differential have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflect the thermal stability for all complexes. The metal- ligand binding of the Ti(IV), Y(III) and Ce(IV) complexes is predicted using density funcational theory at the B3LYP-CEP-31G level of theory and total energy, dipole moment estimation of different Ti(IV), Y(III) and Ce(IV) ofloxacin structures. The biological activities of the ofloxacin, inorganic salts and their metal complexes were assayed against different bacterial species.

• 한국수소및신에너지학회논문집
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• 제35권3호
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• pp.257-268
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• 2024

Hydrogen serves as a clean energy source with potential applications across various sectors including electricity, transportation, and industry. In terms of policy and economic support, governmental policy backing and economic incentives are poised to accelerate the commercialization and expansion of hydrogen energy technologies. Hydrogen energy is set to become a cornerstone for a sustainable future energy system. Additionally, when constructing hydrogen production plants, economic aspects must be considered. The essence of hydrogen production plants lies in the electrolysis of water, a process that separates water into hydrogen and oxygen using electrical energy. The initial capital expenditure (CAPEX) for hydrogen production plants can vary depending on the electrolysis technology employed. This study aims to provide a comprehensive understanding of hydrogen production technologies as well as to propose a method for predicting the CAPEX of hydrogen production plants.

• 전기화학회지
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• 제6권1호
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• pp.41-47
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• 2003

본 연구에서는 중저온에서 작동되는 연료극 지지체식 평판형 연료전지를 연구하였으며, 저가의 공정인 테입케스팅법을 이용하여 $0.8\~1mn$의 두께와 $25,\; 100,\;150cm^2$크기의 평판형 연료극 지지체를 제작하였고, 연료극 지지체의 특성을 확인하기 위해서 기공률, 가스 투과율 그리고 전기전도도 등을 측정하였다. $12wt.\%$의 결합제를 사용하여 제작된 지지체의 기공률은 $45.8\%$이고 환원 시 $53.9\%$로 증가함을 보였다. 연료극 지지체는 $850^{\circ}C$에서 900S/cm의 높은 전기전도도를 나타내었으며, 1기압 하에서 공기로 측정하였을 때 6l/min의 기체투과량을 보였다. 단전지의 제조는 테잎케스팅 법으로 제조된 연료극 지지체위에 슬러리 디핑 코팅법을 이용하여 전해질과 공기극을 순차적으로 제조하였다. YSZ의 농도를 $10wt.\%\;와\;20wt.\%$로 하여 제조된 전해질의 두께는 각각 form와 300m이었고, 공기극은 LSM-YSZ/LSM/LSCF의 다층 구조로 구성되었다. $10{\mu}m$두께의 전해질은 매우 치밀하였고 3기압 하에서 가스 투과도는 2.5ml/min을 나타내었다. 단전지의 성능 시험에서 $20\~30{\mu}m$두께의 전해질을 갖는 연료극 지지체식 평판형 연료전지는 $750^{\circ}C$에서 0.6V, $300 mA/cm^2$성능을 보였다.