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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Electrochemical Society
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Journal DOI :
The Korean Electrochemical Society
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Volume & Issues
Volume 11, Issue 4 - Nov 2008
Volume 11, Issue 3 - Aug 2008
Volume 11, Issue 2 - May 2008
Volume 11, Issue 1 - Feb 2008
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Reduction of Methanol Crossover in a Direct Methanol Fuel Cell by Using the Pt-Coated Electrolyte Membrane
Jung, Eun-Mi ; Rhee, Young-Woo ; Peck, Dong-Hyun ; Lee, Byoung-Rok ; Kim, Sang-Kyung ; Jung, Doo-Hwan ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 1~5
DOI : 10.5229/JKES.2008.11.1.001
A Pt-layer was deposited on the anode side of a Nafion membrane via a sputtering method in order to reduce methanol crossover in a direct methanol fuel cell (DMFC). The methanol permeation and the proton conductivity through the modified membranes were investigated. The performances of the direct methanol fuel cell were also tested using single cells with a Nafion membrane and the modified membranes. The Pt-layers on the membrane blocked both methanol crossover and proton transport through the membranes. Methanol permeability and proton conductivity decreased with an increase of the platinum layer thickness. At methanol concentration of 2 M, the DMFC employing the modified membrane with a platinum layer of 66 nm-thickness showed similar performance to that of a DMFC with a bare Nafion membrane in spite of the lower proton conductivity of the former. The maximum power density of the cell using the modified membrane with a platinum layer of 66 nm-thickness increased slightly while that of the cell with the bare membrane decreased abruptly when a methanol solution of 6M was supplied.
Investigation of Factors Influencing Methanol Crossover in Direct Methanol Fuel Cell
Hyun, Min-Soo ; Kim, Sang-Kyung ; Lim, Seong-Yop ; Lee, Byung-Rock ; Peck, Dong-Hyun ; Jung, Doo-Hwan ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 6~10
DOI : 10.5229/JKES.2008.11.1.006
The amount of methanol crossover was measured with changing the operating condition by using a liquid methanol concentration sensor. Appropriate operating condition was discussed in terms of methanol crossover. Mechanism of methanol crossover was classified into three items which are diffusion, convection and electro-osmosis. Contribution of each mechanism to methanol crossover and the effect of operating condition were analyzed with varying methanol concentration, pressure difference between anode and cathode, current, temperature, and stoichiometry of anode fuel. Among the three mechanisms diffusion affected mostly and electro-osmosis effect was observed only under high methanol concentration.
Composite Membrane Containing a Proton Conductive Oxide for Direct Methanol Fuel Cell
Peck, Dong-Hyun ; Cho, Sung-Yong ; Kim, Sang-Kyung ; Jung, Doo-Hwan ; Kim, Jeong-Soo ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 11~15
DOI : 10.5229/JKES.2008.11.1.011
The composite membrane for direct methanol fuel cell (DMFC) was developed using
powder and perfluorosulfonylfluroride copolymer (Nafion) resin. The perfluorosulfonylfluroride copolymer (Nafion) resin was mixed with
powder and it was made to sheet form by hot pressing. The electrodes were prepared with 60 wt% PtRu/C and 60wt% Pt/C catalysts for anode and cathode, respectively. The morphology and the chemical composition of the composite membrane have been investigated by using SEM and EDXA, respectively. The composite membrane and
were analyzed by using FT-IR and XRD. The methanol permeability of the composite membranes was also measured by gas chromatography (GC). The performance of the MEA containing the composite membrane (2wt%
) was higher than that of normal pure Nafion membrane at high operating temperature (e.g.
), due to the homogenous distribution of
, which decreased the methanol permeability through the membrane and enhanced the water contents in the composite membrane.
Performance of Membrane Electrode Assembly for DMFC Prepared by Bar-Coating Method
Kang, Se-Goo ; Park, Young-Chul ; Kim, Sang-Kyung ; Lim, Seong-Yop ; Jung, Doo-Hwan ; Jang, Jae-Hyuk ; Peck, Dong-Hyun ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 16~21
DOI : 10.5229/JKES.2008.11.1.016
The key component of a direct methanol fuel cell (DMFC) is the membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane and catalyst layers (anode and cathode electrode). Generally the catalyst layer is coated on the porous electrode supporter (e.g. carbon paper or cloth) using various coating methods such as brushing, decal transfer, spray coating and screen printing methods. However, these methods were disadvantageous in terms of the uniformity of catalyst layer thickness, catalyst loss, and coating time. In this work, we used bar-coating method which can prepare the catalyst layer with uniform thickness for MEA of DMFC. The surface and cross-section morphologies of the catalyst layers were observed by SEM. The performances and resistance of the MEAs were investigated through a single cell evaluation and impedance analyzer.
Development of Intermediate Temperature Fuel Cell Using a Solid Proton Conductor
Seo, Dong-Ho ; Kim, Hong-Rok ; Shakkthivel, P. ; Shul, Yong-Gun ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 22~32
DOI : 10.5229/JKES.2008.11.1.022
Because of an emerging importance of clean energy, fuel cells are attract more attention due to their ability to produce high efficient power without any harmful emission. Fuel cells are energy conversion device with directly convert chemical energy into electrical energy by the chemical reactions, which have potential applications in automobile, spacecraft, stationary, industrial and home appliances. Recently there are gaining demand to develop an intermediate temperature fuel cell and available proton conductors at
, which promising operating temperatures range for both material science and energy conversion processes. In this paper, we have reviewed electrochemical properties and current technology of solid state proton conductors. In addition, development of intermediate temperature fuel cell using the perovskite-type solid protonic conductor is also discussed.
Impedance Characteristics of the Gel Type VRLA Battery at the Various State-of-Charge
An, Sang-Yong ; Jeong, Euh-Duck ; Won, Mi-Sook ; Shim, Yoon-Bo ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 33~36
DOI : 10.5229/JKES.2008.11.1.033
In the present study, impedance spectrometry has been used for predicting State-of-Charge (SoC) of gel type, Valve Regulated Lead Acid (VRLA), battery. The impedance measurements of VRLA battery (2V/1.2 Ah) at various SoC were made over the frequency range from 100kHz to 10mHz with an amplitude 10 mV. The impedance parameters have been evaluated by the analysis of the data using an equivalent circuit and a complex non-linear least squares (CNLS) fitting method. The charge transfer resistance values and double layer capacitance values of the positive electrode were higher than those of the negative electrode. The gel resistance values increased with decreasing in SoC. This indicates that the gel resistance is an important parameter for predicting SoC of VRLA battery.
Electrochemical Properties and Structural Analysis of Carbon-Coated Silicon Anode for Lithium Secondary Batteries
Kim, Hyung-Sun ; Chung, Kyung-Yoon ; Cho, Byung-Won ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 37~41
DOI : 10.5229/JKES.2008.11.1.037
The effects of carbon-coated silicon anode on the electrochemical properties and structural change were investigated. The carbon-coated silicon powders have been prepared by thermal decomposition under argon/10wt% propylene mixed gas flow at
. The surface and crystal structure of the synthesized materials were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Lithium cells with electrodes made from the uncoated and the carbon coated silicon anode were assembled and tested. The carbon-coated silicon particles merged together well after the insertion/extraction of lithium ions, and showed a relatively low irreversible capacity compared with the uncoated silicon particle.
Effect of Carbon Dioxide in Fuel on the Performance of PEMFC
Seo, Jung-Geun ; Kwon, Jun-Taek ; Kim, Jun-Bom ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 42~46
DOI : 10.5229/JKES.2008.11.1.042
Even though fuel cell have high efficiency when pure hydrogen from gas tank is used as a fuel source, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO,
in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of the electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of
, 20% or less of
, 5.8% of less of
, or 2% less of
, and 10ppm or less of CO. This study is aimed at investigating the effect of carbon dioxide on fuel cell performance. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run(10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC).
High Coulombic Efficiency Negative Electrode(SiO-Graphite) for Lithium Ion Secondary Battery
Shin, Hye-Min ; Doh, Chil-Hoon ; Kim, Dong-Hun ; Kim, Hyo-Seok ; Ha, Kyung-Hwa ; Jin, Bong-Soo ; Kim, Hyun-Soo ; Moon, Seong-In ; Kim, Ki-Won ; Oh, Dae-Hui ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 47~50
DOI : 10.5229/JKES.2008.11.1.047
A new anode composition material comprising of SiO and Graphite has been prepared by adopting High energy ball milling (HEBM) technique. The anode material shows high initial charge and discharge capacity values of 1139 and 568 mAh/g, respectively. The electrode sustains reversible discharge capacity value of 719 mAh/g at 30th cycle with a high coulombic efficiency
. Since the materials formed during initial charge process the nano silicon/
remains as interdependent, it may be expected that the composite exhibiting higher amount of irreversibility
will deliver higher reversible capacity. In this study, constant current-constant voltage (CC-CV) charge method was employed in place of usual constant current (CC) method in order to convert efficiently all the SiO particles which resulted high initial discharge capacity at the first cycle. We improved considerably the initial discharge specific capacity of SiO/G composite by pretreatment(CC-CV).
Three Dimensional Computational Study on Performance and Transport Characteristics of PEMFC by Flow Direction
Lee, Pil-Hyong ; Han, Sang-Seok ; Hwang, Sang-Soon ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 51~58
DOI : 10.5229/JKES.2008.11.1.051
Many researches for effects of different flow configurations on performance of Proton Exchange Membrane Fuel Cell have extensively been done but the effects of flow direction at the same flow channel shape should be considered for optimal operation of fuel cell as well. In this paper a numerical computational methode for simulating entire reactive flow fields including anode and cathode flow has been developed and the effects of different flow direction at parallel flow was studied. Pressure drop along the flow channel and density distribution of reactant and products and water transport, ion conductivity across the membrane and I-V performance are compared in terms of flow directions(co-flow or counter-flow) using above numerical simulation method. The results show that the performance under counter-flow condition is superior to that under co-flow condition due to higher reactant and water transport resulting to higher ion conductivity of membrane.
The Potentiometric Performance of Mercury (II) Ion-Selective Electrode Based on Tetracycline Antibiotics
Baek, Jong-Gyu ; Rhee Paeng, In-Sook ;
Journal of the Korean Electrochemical Society, volume 11, issue 1, 2008, Pages 59~63
DOI : 10.5229/JKES.2008.11.1.059
Poly (vinylchloride) (PVC) membrane electrodes based on neutral carrier, tetracycline was prepared as an active sensor for Hg(II) ion, and tested in different contents of the potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as lipophilic salt. Bis (2-ethylhexyl) sebacate (DOS), bis(l-butylpentyl) adipate (BBPA), 2-nitrophenyl octyl ether (NPOE) and dibutyl phthalate (DBP) were used as diverse plasticizing solvent mediators. This electrode shows excellent potentiometric response characteristics and display good linearity with log
versus EMF response, over a range of concentrations between
. With 30.8mV/decade Nernstian slope, the detection limit was
and the response time was less than 20s. The proposed electrode yields very good selectivity for mercury (II) ion over many cations such as alkali, alkaline earth, transition and heavy metal ions. And it shows a very stable potential values in a wide pH range. This reliable electrode prepared was kept at least a month without considerable alteration in their response to Hg (II) ion.