• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.17-23
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• 2017

Polyether ether ketone (PEEK) composite including tungstophosphoric acid(TPA) membranes have been intensively investigated for polymer electrolyte membrane water electrolysis (PEMWE) and thus covalently linked sulfonated polyether ether ketone (CL-SPEEK) with captured TPA composite membranes were prepared and characterized. Sulfonated polyether ether ketone (SPEEK) was prepared in sulfonation of PEEK and was cross-linked with 1,4 diiodobutane. The carbonyl group of SPEEK was reduced with $NaBH_4$ and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The TPA captured composite was prepared in reaction of TPA with 3-mercaptopropyltrime thoxysilane (MPTMS). The polymer composite membranes showed better thermostability and electrochemical properties than SPEEK. The membranes were prepared by sol-gel casting method. The polymer composite membrane featured 0.1285 S/cm of proton conductivity at $80^{\circ}C$ and outstanding durability.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.5
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• pp.478-484
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• 2016

Polyether ether ketone (PEEK) composite membranes have been intensively investigated for polymer electrolyte membrane water electrolysis (PEMWE). Covalently linked (CL) sulfonated polyether ether ketone (SPEEK) and cellulose polymer composite membranes were prepared and characterized. Polyether ether ketone (PEEK) and cellulose were sulfonated and then were covalently linked by 1,4-diiodobutane to produce covalently linked SPEEK and cellulose polymer composite membranes. The composite membranes showed better thermostability and electrochemical properties than SPEEK. The membranes were prepared by sol-gel casting method. CL-SPEEK/Cellulose composite membrane featured 0.2453 S/cm of proton conductivity at $80^{\circ}C$ which was better than that of Nafion.

• Membrane Journal
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• v.25 no.6
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• pp.538-546
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• 2015

In this study, composite membrane is prepared by Layer-by-Layer method using hydrophobic polymer as a coating material on the polysulfone support. The existence of coating layer on the surface and cross section was confirmed by the scanning electronic microscopy. The flux and rejection of the resulting membranes were characterized using 100 ppm NaCl feed solution. PVSA, PEI, PAA, PSSA, PSSA_MA were used as a coating polymer in this study. The composite membrane prepared by using 8,000 ppm PAA solution (Ion strength = 0.35, Coating time = 3 min) and 10,000 ppm PEI solution (Coating time = 4 min). As a result, PAA-PEI composite membrane showed flux of 101 LMH and salt rejection of 66.7%. The composite membrane showed the comparable performance as good as NE 4040-70 (Flux = 30 LMH, Rejection = 40~70%) model produced by Toray Chemical co.

• Membrane Journal
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• v.19 no.1
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• pp.63-71
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• 2009

In this study, polysulfone which has excellent mechanical and thermal stability with low cost was used for preparing a non-conducting polymer matrix as a reinforced composite membrane for fuel cell application. The membranes were prepared by phase separation method. Polymer concentration and retention time were controlled to investigate the effects on the membrane morphology. The resaltant membranes showed all sponge-like structure independent of polymer concentration. The mechanical and thermal stability were improved with increasing polymer concentration in contrast to the membrane porosity. As a result, the membranes prepared with the retention time for 2 mins using 20 wt% of polymer solution was suitable for a fuel cell compositite membrane providing optimum properties such as approximately 80% of high porosity, 1.3 MPa of tensile strength, and less than 1% of thermal shrinkage both machine and transverse direction.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.28-38
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• 2014

The organic-inorganic composite membrane in polymer exchange membrane fuel cells (PEMFCs) have several fascinating technological advantages such as a proton conductivity, thermal stability and mechanical properties. As the inorganic filler, silicon carbide (SiC) fiber have been used in various fields due to its unique properties such as thermal stability, conductivity, and tensile strength. In this study, composite membrane was successfully fabricated by modified-silicon carbide fiber. Modified process, as a novel process in SiC, takes reaction by phosphoric acid after oxidation process (generated homogeniusly $SiO_2$ layer on SiC fiber). The mechanical property which was conducted by tensile test of the 5wt% modified-$SiO_2@SiCf$ composite membrane was better than that of Aquivion casting membrane as well as ion cxchange capacity(IEC) and proton conductivity. In addition, the single cell performance was observed that the 5wt% modified-$SiO_2@SiCf$ composite membrane was approximately $0.2A/cm^2$ higher than that of a Aquivion casting electrolyte membrane and electrochemical impedance was improved with the charge transfer resistance and membrane resistance.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.11-15
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• 2008

The composite membrane for direct methanol fuel cell (DMFC) was developed using $H_3O^+-{\beta}"-Al_2O_3$ powder and perfluorosulfonylfluroride copolymer (Nafion) resin. The perfluorosulfonylfluroride copolymer (Nafion) resin was mixed with $H_3O^+-{\beta}"-Al_2O_3$ 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 $H_3O^+-{\beta}"-Al_2O_3$ 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% $H_3O^+-{\beta}"-Al_2O_3$) was higher than that of normal pure Nafion membrane at high operating temperature (e.g. $110^{\circ}C$), due to the homogenous distribution of $H_3O^+-{\beta}"-Al_2O_3$, which decreased the methanol permeability through the membrane and enhanced the water contents in the composite membrane.

• Macromolecular Research
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• v.14 no.4
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• pp.449-455
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• 2006

Ionic cluster mimic, polymer electrolyte membranes were prepared using polymer composites of crosslinked poly(vinyl alcohol) (PVA) with sulfated-${\beta}$-cyclodextrins (${\beta}-CDSO_3H$) or phosphated-${\beta}$-cyclodextrins (${\beta}-CDPO(OH)_2$). When Nafion, developed for a fuel cell using low temperature, polymer electrolyte membranes, is used in a direct methanol fuel cell, it has a methanol crossover problem. The ionic inverted micellar structure formed by micro-segregation in Nafion, known as ionic cluster, is distorted in methanol aqueous solution, resulting in the significant transport of methanol through the membrane. While the ionic structure formed by the ionic sites in either ${\beta}-CDSO_3H$ or ${\beta}-CDPO(OH)_2$ in this composite membrane is maintained in methanol solution, it is expected to reduce methanol transport. Proton conductivity was found to increase in PVA membranes upon addition of ionized cyclodextrins. Methanol permeability through the PVA composite membrane containing cyclodextrins was lower than that of Nafion. It is thus concluded that the structure and fixation of ionic clusters are significant barriers to methanol crossover in direct methanol fuel cells.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.109-112
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• 2004

The charged mosaic membranes having cation and anion exchange mixed groups within membrane were researched. The composite charged mosaic membrane was investigated from simultaneous transport such as solute and solvent flux. On the other hand, the reflection coefficient and salt flux coefficient were estimated by taking account of the cross constants of the phenomenological equation.(omitted)

• Composites Research
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• v.34 no.6
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• pp.373-379
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• 2021

A series of novel PBI/SrTiO₃ nanocomposite membranes composed of polybenzimidazole (PBI) and strontium titanate (SrTiO₃) with a perovskite structure were fabricated with various concentrations of SrTiO₃ through a solution casting method. Various characterization techniques such as proton nuclear magnetic resonance, thermogravimetric analysis, atomic force microscopy (AFM) and AC impedance spectroscopy were used to investigate the chemical structure, thermal, phosphate absorption and morphological properties, and proton conductivity of the fabricated nanocomposite membranes. The optimized PBI/SrTiO₃-8 polymer nanocomposite membrane containing 8wt% of SrTiO₃ showed a higher proton conductivity of 7.95 × 10^-2 S/cm at 160℃ compared to other nanocomposite membranes. The PBI/SrTiO₃-8 composite membrane also showed higher thermal stability compared to pristine PBI. In addition, the roughness change of the polymer composite membrane was also investigated by AFM. Based on these results, nanocomposite membranes based on perovskite structures are expected to be considered as potential candidates for high-temperature PEM fuel cell applications.

• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.45-49
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• 2016

In order to mitigate oxidative degradation of polymer membrane during fuel cell operation, an organic radical quencher was introduced. Rutin was selected as a radical quencher and mixed with sulfonated poly(arylene ether sulfone) to prepare composite membrane. Physicochemical properties of the composite membranes such as water uptake and proton conductivity were characterized. Hydrogen peroxide exposure experiment, which can mimic accelerated oxidative stability test during fuel cell operation, was adopted to evaluate the oxidative stability of the membranes. The composite membranes containing Rutin showed similar proton conductivity and enhanced oxidative stability compared to pristine ones.