• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.497-501
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• 2011

Polymer electrolyte membrane fuel cell (PEMFC) performance degrade when sulfur dioxide is present in the fuel hydrogen gas, this is referred as $SO_2$ poisoning. This paper reveals $SO_2$ poisoning on PEMFC cathode part by measuring electrical performance of single cell under 1 ppm and 5 ppm on $SO_2$ gas operating. The security of $SO_2$ poisoning depended on $SO_2$ concentration under the best operating conditions($65^{\circ}C$ of cell temperature and 100% of relative humidity between anode and cathode). $SO_2$ adsorption occured on the surface of catalyst layer on membrane electrode assembly (MEA), In addition, MEA poisoning by $SO_2$ was cumulative but reversible. After poisoning within 5 ppm $SO_2$ for 1hr, the electrical performance of PEMFC was found to recover up to about 93% by cyclic voltametry scan.

• Rubber Technology
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• v.6 no.2
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• pp.91-98
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• 2005

Nano-sized cathode materials for high power lithium ion polymer battery are easily and economically prepared using united eutectic self-mixing method without any artificial mixing procedures of reactants and ultra-miniaturization of products. While the micro-sized $LiNi_{0.7}Co_{0.3}O_2$ exhibits the discharge capacities of 167.8 mAh/g at 0.1C and 142.5 mAh/g at 3.0C, those of the nano-sized $LiNi_{0.7}Co_{0.3}O_2$ are 170.8 mAh/g at 0.1C and 159.3 mAh/g at 3.0C. In the case of $LiCoO_2$, the micro-sized $LiCoO_2$ exhibits the discharge capacities of 134.8 mAh/g at 0.1C and 118.6 mAh/g at 5.0C. Differently, the nano-sized $LiCoO_2$ exhibits the discharge capacities of 137.2 mAh/g at 0.1C and 131.7 mAh/g at 5.0C.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.362-363
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• 2008

Well-defined o-$LiMnO_2$ cathode materials were synthesized using LiOH and $Mn_3O_4$ starting materials at $1050^{\circ}C$ in an argon flow by quenching method. The synthesized $LiMnO_2$ particles with crystalline phases were identified with X-ray diffraction (XRD, Dmax/1200, Rigaku). XRD results, demonstrated that the compound $LiMnO_2$ can be indexed to a single-phase material having the orthorhombic structure. In this paper, we analyzed the electrochemical performance of $LiMnO_2$/Li using solid polymer electrolyte and liquid electrolyte.

• Advances in materials Research
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• v.4 no.2
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• pp.113-132
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• 2015

The phenomena of high-voltage polarization and conductivity in oriented vinylidenefluoride and tetrafluoroethylene copolymer films have been investigated. It was shown that under certain electric fields, injection of carriers from the material of electrodes appears The barrier for holes injection in the copolymer was found to be lower than that for electrons. It results in more effective screening of the external field near the anode than near cathode. Electrones, ejected from cathode, creating negative charge by trapping on the surface. It is shown that the electrons injected from cathodes create a negative homocharge on the copolymer surface and then become captured on the surface shallow traps. Their nature has been studied by the x-ray photoelectron spectroscopy. It was shown that these traps may consist of chemical defects in the form of new functional groups formed by reactions of surface macromolecules with sputtered atoms of aluminum. The asymmetric shape of hysteresis curves was explained by the difference in mobility of injected holes and electrons. These factors caused appearance of "non-closed" hysteresis curves for fluorine-containing polymer ferroelectrics. Hysteresis phenomena observed at low electric fields (below coercive ones) are to associate with the behavior of the domains localized in the ordered regions formed during secondary crystallization of copolymers.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.476-483
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• 2012

Proper water management is crucial for the efficient operation of polymer electrolyte membrane (PEM) fuel cell. Especially, for automotive applications, A novel water management that can avoid both membrane dry-out and flooding is a very important task to achieve good performance and efficiency of PEM fuel cells. The aim of this study is to investigate the liquid water behavior on the gas diffusion layer (GDL) surface and in the cathode flow channel of a PEM unit fuel cell under flooding conditions. For this purpose, a transparent unit fuel cell is devised and fabricated by modifying the conventional PEM fuel cell design. The results of water droplet behavior under flooding conditions are mainly presented. The water distributions in the cathode flow channels with cell operating voltage are also compared and analyzed. Through this work, it is expected that the data obtained from this fundamental study can be effectively used to establish the basic water management strategy in terms of water removal from the flow channels in a PEM fuel cell stack.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.340-347
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• 2022

In this research, mixed metal oxide (TiO₂, RuO₂) coating was applied to grade 1 titanium as a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Electrochemical experiments were carried out in an aqueous solution of pH 3 (H₂SO₄ + 0.1 ppm HF, 80 ℃) determined by DoE. The air was bubbled to simulate a cathode environment. Potentiodynamic polarization test revealed that corrosion current densities of the titanium substrate and MMO-coated specimen were 0.180 µA/cm² and 4.381 µA/cm², respectively. There was no active peak. After potentiostatic experiment, current densities of the titanium substrate and the MMO-coated specimen were 0.19 µA/cm² and 1.05 µA/cm², respectively. As a result of observing the surface before and after the potentiostatic experiment, cracked dried clay structures were observed without corrosion damage. Both the titanium substrate and the MMO-coated specimen could not satisfy the interfacial contact resistance suggested by the DoE. Thus, further research is needed before they could be applied as bipolar plates.

• Polymer(Korea)
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• v.31 no.1
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• pp.74-79
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• 2007

Polypyrrole (PPy) was made by an emulsion polymerization using iron (III) chloride ($FeCl_3$) as an initiator and dodecyl benzene sulfuric acid (DBSA) as an emulsifier and dopant. Poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) was sulfonated by chlorosulfonic acid (CSA). The cathode was composed of $PPy^+DBS^-$ complex, conductor powder, and PPO or sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO) as a binder or dopant. The charge-discharge performance of $PPy^+DBS^-/SPPO$ cathode was increased as the extent of about 50%, than $PPy^+DBS^-/PPO$. This is because SPPO played a role as a binder as well as a dopant. In addition, sulfonation brings out the increase of miscibility between PPy and SPPO, and the increase of contact area between cathode and electrolyte.

• Journal of the Korean Applied Science and Technology
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• v.29 no.4
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• pp.594-598
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• 2012

Polymer electrolyte membrane fuel cell(PEMFC) performance degrades seriously when sulfur dioxide and hydrogen sulfide are contaminated in the fuel gas at anode and air source at cathode, respectively. This paper reveals the effect of the combined sulfur impurity poisoning on both PEMFC cathode and anode parts through measuring electrical performance on single FC operated under 1 ppm to 10 ppm impurity gases. The severity of $SO_2$ and $H_2S$ poisoning depended on concentrations of impurity gases under optimum operating conditions($65^{\circ}C$ of cell temperature and 100 % relative humidity). Sulfur adsorption occured on the surface of Pt catalyst layer on MEA. In addition, MEA poisoning by impurity gases were cumulative. After four consecutive poisonings with 1, 3, 5 to 10 ppm, the fuel cell performance of PEMFC was decrease upto 0.54 V(76 %) from 0.71 V.

• Analytical Science and Technology
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• v.8 no.3
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• pp.265-272
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• 1995

Schiff base ligand columns and glow discharge detector have been developed for the trace analysis of metal ions desolved in water. Various types of hydrazide Schiff base ligands have been used and, additionally, they were examined as a filling material of a HPLC column. The hydrazide Schiff base ligands used were N, N'-oxalybis(salicylaldehydrazone) (OBSH), N, N'-malonylbis(salicylaldehydrazone) (MBSH), and N, N'-succinylbis(salicylaldehydrazone) (SBSH). A mixture of Schiff base ligand and poly(styrene divinylbenzene) was examined and it showed a smooth flow of solution. The OBSH-polymer column demonstrated different effluent factors for different metal ions. Metal ions in eluates were detected by Hollow Cathode Glow Discharge-Atomic Emission Spectrometry(HCGD-AES). HCGD-AES showed good sensitivity and selectivity. This is only the preliminary results of new OBSH-polymer column and glow discharge detector.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.767-770
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• 2009

We synthesized a spirobenzofluorene type phosphine oxide (SPPO2) as a new triplet host and an universal electron transport material for phosphorescent organic light-emitting diodes(PHOLEDs). Red PHOLEDs with the SPPO2 host material showed a high quantum efficiency of 14.3 % with a current efficiency of 20.4 cd/A. In addition, the SPPO2 could be applied as an electron transport material which can be matched with any host material due to the lowest unoccupied molecular orbital of 2.4 eV. Electron injection from a cathode to the SPPO2 electron transport layer was better than common electron transport materials. In particular, the SPPO2 was effective as the electron transport material in blue PHOLEDs and the quantum efficiency was more than doubled and driving voltage was lowered by more than 3 V using the SPPO2 instead of common electron transport material.