• Membrane Journal
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• v.5 no.3
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• pp.109-118
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• 1995

In this study, cell resistivity and membrane resistivity were measured in Fe-Cr redox-fiow battery system using commercial ion-exchange membranes. Cell resistivity and membrane resistivity at charging periods are higher than at discharging periods. And at the same membrane the resistivity were increased with increasing SOC. The resistivity of hydrocarbon type Seiemion CMV membrane was smaller than perfluoro type Nafion 117 and Nafion 551. The cell resistivity and membrne resistivity of CMV membrane at 0 % SOC was $12.864\Omega \textrm{cm}^2$ and $8.751\Omega \textrm{cm}^2$, respectively.

• Membrane Journal
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• v.12 no.3
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• pp.143-150
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• 2002

Electrodialysis(ED) is a reliable and effective process for the separation and concentration of ionic compounds. However, commercial uses of ED are often hindered by the cost of the stack that mainly resulted from the ion-exchange membrane cost. In order to minimize the membrane cost, it is desired to operate ED at the highest practicable current density. In an actual ED system the high current operation is limited by the concentration polarization phenomenon. This article illustrates the transport phenomena of ions through ion exchange membranes using current-voltage relations as a characterizing method. Also recent studies on electroconvection and water-spitting phenomena caused by concentration polarization were reviewed.

• Membrane Journal
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• v.31 no.6
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• pp.371-383
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• 2021

Anion exchange membranes have been used for water electrolysis, which can produce hydrogen, and fuel cells, which can generate electrical energy using hydrogen fuel. Anion exchange membranes operate based on hydroxide ion (OH^-) conduction under alkaline conditions. However, since the anion exchange membrane shows relatively low ion conductivity and alkaline stability, there is still a limit to its commercialization in water electrolysis and fuel cells. To address these issues, it is important to develop novel anion exchange membrane materials by rationally designing a polymer structure. In particular, the polymer structure and synthetic method need to be controlled. By doing so, for polymers, the physical properties, ionic conductivity, and alkaline stability can be maintained. Among many anion exchange membranes, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is commercially available and easily accessible. In addition, the PPO has relatively high mechanical and chemical stability compared to other polymers. In this review, we introduce the recent development strategy and characteristics of PPO-based polymer materials used in anion exchange membranes.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.151-157
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• 2011

Crosslinked SPEEK/PVDF membrane were prepared by EB radiation method with various contents of PVDF. The prepared membranes were subjected to a comparative study of proton exchange membranes for fuel cell appreciations. The crosslinked SPEEK/PVDF membranes were characterized by using DMA, DSC and SAXS. The DMA data indicate that the ionic modulus values and cluster $T_g$ decrease with increasing PVDF content. Thus, it was suggested that the number of clustering in the crosslinked membranes can be reduced with increasing PVDF content. The DSC results were shown that the degree of crystalline of the membrane increased with increasing PVDF content. The morphology of the crosslinkied membranes was shown that with increasing PVDF content, the number of crystalline domain of the SPEEK/PVDF membranes increased but ionic aggregation of the membranes decreased. The water uptake behavior, ionic exchange capacity (IEC) and proton conductivity were decreased with increasing PVDF content. The overall findings suggest that the crosslinked membranes offer the possibility for improving the performance of PEMFC, provided that the membranes have thermal and hydration stability.

• Membrane Journal
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• v.14 no.1
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• pp.44-52
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• 2004

This paper concerns the development of a cationic polymeric membranes for direct methanol fuel cell. The crosslinked poly(vinyl alcohol) (PVA) membranes with poly(acrylic acid-co-maleic acid) (PAM) and hydroquinonesulfonic acid (HQSA) as the crosslinking agents were prepared according to the amount of crosslinking agents. The resulting membranes were characterized in terms of methanol permeability, proton conductivity, water content and ion exchange capacity. The methanol permeability and proton conductivity increased with increasing PAM content up to 9 wt% and then decreased. This trend is considered the effect of the cross linking rather than the introduction of hydrophilic groups. When the HQSA contents were varied, no interesting increases of proton conductivity, water content and ion exchange capacity were found.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.621-626
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• 2010

Anion exchange membranes can be used for reverse electrodialysis for electric energy generation, and capacitive deionization for water purification, as well as electrodialysis for desalination. In this study, anion exchange membranes of poly((vinylbenzyl) trimethylammonium chloride-2-hydroxyethyl methacrylate)/poly(vinyl alcohol) were prepared through the polymerization of (vinylbenzyl)trimethylammonium chloride and 2-hydroxyethyl methacrylate in aqueous poly(vinyl alcohol) solutions, esterification with glutaric acid, and cross-linking reaction with glutaraldehyde. We investigated electrochemical properties for the anion exchange membranes prepared according to experimental conditions. Ion exchange capacity and electrical resistance for the membranes were changed with a variation in the monomer ratio in polymerization. Water uptake and conductivity for the membranes decreased with an increase in the content of glutaric acid in esterification. The change in the time of crosslinking reaction with the formed film and glutaraldehyde affected electrochemical properties such as water uptake, conductivity, or transport number for the membranes. Chronopotentiometry and limiting current density for the anion exchange membranes prepared were measured.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1651-1655
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• 2013

Anion exchange membranes for a vanadium redox flow battery (VRB) were prepared by pore-filling on a PE substrate with the copolymerization of vinylbenzyl chloride (VBC) and glycidyl methacrylate (GMA). The ion exchange capacity, water uptake and weight gain ratio were increased with a similar tendency up to 65% of GMA content, indicating that the monomer improved the pore-filling degree and membrane properties. The vanadium ion permeability and open-circuit voltage were also investigated. The permeability of the VG65 membrane was only $1.23{\times}10^{-7}\;cm^2\;min^{-1}$ compared to $17.9{\times}10^{-7}\;cm^2\;min^{-1}$ for Nafion 117 and $1.8{\times}10^{-7}\;cm^2\;min^{-1}$ for AMV. Consequently, a VRB single cell using the prepared membrane showed higher energy efficiency (over 80%) of up to 100 cycles compared to the commercial membranes, Nafion 117 (ca. 58%) and AMV (ca. 70%).

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.150-153
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• 2009

Anion exchange polymer electrolyte pore-filling membranes consisting of the whole hydrocarbon materials were prepared by photo polymerization with various quaternary ammonium cationic monomers and characterized on the properties for applying to solid alkali fuel cell (SAFC). Hydrocarbon porous substrates such as polyethylene were used for the preparation of the pore-filling membranes. The hydroxyl ion conductivity of the polymer electrolyte membranes prepared in this research was dependent on the composition ratio of an electrolyte monomer and crosslinking agents used for polymerization. Furthermore, these pore-filling membranes have commonly excellent properties such as smaller dimensional affects when swollen in solvents, higher mechanical strength, lower fuel crossover through the membranes, and easier preparation process than those of traditional cast membranes.

• Macromolecular Research
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• v.13 no.4
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• pp.314-320
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• 2005

Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from $10^{-3}\;to\;10^{-2}S/cm$ and the methanol permeabilities from $10^{-7}\;to\;10^{-6}cm^{2}/sec$. In addition, the effect of operating temperature up to $80^{\circ}C$ on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at $80^{\circ}C$, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, $7{\sim}9\;wt%$ PAM membrane prepared at $140^{\circ}C$ exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

• Membrane Journal
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• v.21 no.1
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• pp.91-97
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• 2011

In this study, the anionic exchange membranes were prepared through the impregnation of polyethylenimine (PEI) into porous polyethylene (PE) separator and then crosslinking with isophrhaloyl dichloride (IPC). To characterize the resulting membranes, the contact angles, FT-IR, ion exchnage capacity and ion conductivity were measured. The amide group is produced the reaction between amines in PEI and -COCl in IPC. In case of ion exchange capacity, 1.96 meq./g dry membrane at the reaction time, 30 sec was decreased to 1.14 meq./g dry membrane at 600 sec reaction time. The ion conductivity, $9.15{\times}10^{-2}S/cm$ at 30 sec reaction time, was obtained.