• Journal of the Korean Electrochemical Society
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• v.18 no.4
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• pp.150-155
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• 2015

In this study polymer electrolytes containing ethylene carbonate group which have a high dielectric constant and poly(ethylene glycol) as branches were prepared by the Williamson reaction between poly(ethylene glycol) methyl ether and block copolymers composed of glycerol-1,2-carbonate and 4-chloromethyl styrene. Interestingly, the highest ionic conductivity of $1.75{\times}10^{-5}S\;cm^{-1}$ was observed from the polymer electrolyte having 7 mol% of ethylene carbonate and the [EO]:[Li] ratio of 32:1. Moreover, it was found that the electrochemical stability of polymer electrolyte was achieved up to 5.5 V because of the presence of ethylene carbonate.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.101-106
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• 2016

In this study, we prepared an ionic liquid composite solid polymer electrolyte (PEO-LiTFSI-$Pyr_{14}TFSI$) with poly(ethylen oxide), lithium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide by blending-cross linking process. Although the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte displayed a small peak at 4.4 V, it had high electrochemical oxidation stability up to 5.7 V. Ionic conductivity of the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte increased with increasing temperature from $10^{-6}S\;cm^{-1}$ at $30^{\circ}C$ to $10^{-4}S\;cm^{-1}$ at $70^{\circ}C$. To investigate the electrochemical properties, the PEO-LiTFSI-$Pyr_{14}TFSI$ composite solid polymer electrolyte assembled with $LiFePO_4$ cathode and Li-metal anode. At 0.1 C-rate, the cell delivered $40mAh\;g^{-1}$ for $30^{\circ}C$, $69.8mAh\;g^{-1}$ for $40^{\circ}C$ and $113mAh\;g^{-1}$ for $50^{\circ}C$, respectively. The PEO-LiTFSI-$Pyr_{14}TFSI$ solid polymer electrolyte exhibited good charge-discharge performance in Li/SPE/$LiFePO_4$ cells at $50^{\circ}C$.

• Membrane Journal
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• v.32 no.6
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• pp.442-455
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• 2022

High-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) has been studied as an alternative to low-temperature PEMFC due to its fast activation of electrodes and high resistance to electrode poisoning by carbon monoxide. It is highly required to develop stable PEMs operating at high temperatures even doped by ion-conducting materials for the development of high-performance and durable HT-PEMFC systems. A number of studies have been conducted to develop polybenzimidazole (PBI)-based PEMs for applications in HT-PEMFC due to their high interaction with doped ion-conducting materials and outstanding thermomechanical stability under high-temperature operation. This review focused on the development of PBI-based PEMs showing high performance and durability. Firstly, the characteristic behavior of PBI-based PEMs doped with various ion-conducting materials including phosphoric acid was systematically investigated. And then, a comparison of the physicochemical properties of the PEMs according to the different membrane manufacturing processes was conducted. Secondly, the incorporation of porous polytetrafluoroethylene substrate and/or inorganic composites to PBI matrix to improve the membrane performances was studied. Finally, the construction of cross-linked structures into PBI-based PEM systems by polymer blending method was introduced to improve the PEM properties.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.12
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• pp.698-704
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• 2000

Mechanical performances of beam shaped and bridge-shaped conductive polymer actuator have been measured and analyzed varying polymerization conditions and operating conditions such as applied current, polymerizing time, frequency of the current and kinds of electrolytes. For the application of conductive polymer actuator to micropump, the diaphragm structure has been fabricated, which is composed of polypyrrole, solid polymer electrolyte and parylene. Measured results how the possibility of the practical application of conductive polymer actuator.

• Macromolecular Research
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• v.17 no.10
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• pp.729-733
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• 2009

Solution casting films of sulfonated poly[styrene-b-(ethylene-r-butylene)-b-styrene] copolymer (sSEBS)-based composite membranes that contained different amounts of organic, nanorod-shaped polyrotaxane were annealed at various temperatures for 1 h. The films' properties were characterized with respect to their use as polymer electrolyte membranes in direct methanol fuel cells (DMFCs). Different aspect ratios of polyrotaxane were prepared using the inclusion-complex reaction between $\alpha$-cyclodextrin and poly(ethylene glycol). The presence of the organic polyrotaxane inside the membrane changed the morphology during the membrane preparation and reduced the transport of methanol. The conductivity and methanol permeability of the composite membranes decreased with increasing polyrotaxane content, while the annealing temperature increased. All of the sSEBS-based, polyrotaxane composite membranes annealed at $140^{\circ}C$ showed a higher selectivity parameter, suggesting their potential usage for DMFCs.

• Applied Microscopy
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• v.47 no.3
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• pp.101-104
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• 2017

In this investigation, synchrotron X-ray imaging was used to investigate the water distribution inside newly developed gas diffusion media in polymer electrolyte membrane fuel cells. In-situ radiography was used to reveal the relationship between the structure of the microporous layer (MPL) and the water flow in a newly developed MPL equipped with randomly arranged holes. A strong influence of these holes on the overall water transport was found. This contribution provides a brief overview to some of our recent activities on this research field.

• Bulletin of the Korean Chemical Society
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• v.23 no.5
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• pp.683-687
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• 2002

We have investigated the effect of the number of ethylene oxide (EO) units inside poly(ethylene glycol)dimethacrylate (PEGDMA) on the ionic conductivity of its gelled polymer electrolyte, whose content ranges from 50 to 80 wt%. PEGDMA gelled polym er electrolytes, a crosslinked structure, were prepared using simple photo-induced radical polymerization by ultraviolet light. The effect of the number of EO on the ionic conductivity was clearly shown in samples of lower liquid electrolyte content. We have concluded that the ionic conductivity increased in proportion to both the number of EO units and the plasticizer content. We have also studied the electrochemical properties of 13PEGDMA (number of EO units is 13) gelled polymer electrolyte.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.277-280
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• 2005

Air-breathing polymer electrolyte membrane fuel cells (PEMFC) are highly promising particularly for small-power applications up to tens watts class. A distinctive feature of the air-breathing PEMFC is its simple system configuration in which axial fans operate for dual purposes, supplying both oxidant and coolant in a single manner. In the present study, a nominal SOW air-breathing PEMFC system is developed and investigated to determine the optimal operating strategy through parametric studies (i.e., reactant humidity, and fan-blowing flow rate). The cell voltage distributions are examined as a function of time to evaluate the system performance under various operating conditions.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.320-323
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• 2006

A numerical study is made of a manifold and bipolar plate in polymer electrolyte fuel cells, the aim of the present study is to describe the characteristics of flow pattern In manifold and bipolar plate. The present work shows that the flow pattern in the bipolar plate is affected by the penetration flow through GDL characterized by clamping pressure and GDL intrusion in to a channel area. Manifold geometry also affects the flow distribution. The recirculation flow by bent duct destroy even distribution In manifold, the present work shows that corner rounding can improve the manifold performance.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.283-290
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• 2009

This study focuses on the performance characteristics of polymer electrolyte membrane fuel cell (PEMFC) using the AC impedance technique. The experiment was carried out to investigate the optimal operating conditions of PEMFC such as cell temperature, flow rate, humidified temperature and back-pressure. The fuel cell performance was analyzed by DC electronic-loader with constant voltage mode and expressed by voltage-current density. Additionally, AC impedance was measured to analysis of ohmic and activation loss and expressed by Nyquist plot. The results showed that the cell performance increased with increase of cell temperature, air flow rate, humidified temperature and backpressure. Also, the activation loss decreased as the increase of cell temperature, air flow rate, humidified temperature and backpressure.