• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.177-179
• /
• 2007

An object of the present study is to provide a hollow fiber membrane humidifier capable of improving the humidification efficiency while lowering the pressure loss, and is suitably usable for PEMFC(Polymer Electrolyte Membrane Fuel Cell). The performance of PEMFC is decisively dependent on the humidity of the electrolyte membrane(fluorinated membrane) and a humidifier plays an important role in moisturizing electrolyte membrane. Especially, this humidifier is a passive type(power-free) item and is volumetrically optimized. In this research, we propose the substitutes for the expensive fluorinated humidifier materials and the optimum dry-jet wet spinning conditions of hollow fiber membrane. In addition to that, This study will present an performance of an humidifier and compare computational results with the experimental data.

• Membrane Journal
• /
• v.15 no.4
• /
• pp.355-362
• /
• 2005

A PFCB-containing biphenylene ether polymer was synthesized and sulfonated using chlorosulfonic acid and then cast into membranes from their solutions for fuel cell applications. Sulfonation reactions were carried out by changing the molar ratio of chlorosulfonic acid and the PFCB-containing biphenylene ether polymer under fixed time and temperature. The resulting sulfonated polymers showed different sulfonation degree (SD), ion exchange capacity (IEC), and water uptake. With the increment of the content of chlorosulfonic acid, the SD, IEC, water uptake of the sulfonated polymer membranes increased. The ion conductivity of the sulfonated PFCB-containing biphenylene ether polymers was compared with that of Nafion 115.

• Korean Journal of Materials Research
• /
• v.20 no.4
• /
• pp.187-193
• /
• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.2
• /
• pp.144-154
• /
• 2016

HT-PEMFC (high temperature polymer electrolyte membrane fuel cell) using PA (phosphoric acid) doped PBI (polybenzimidazole) membrane has been researched for extending the lifetime. However, the existing work on durability of HT-PEMFC focuses on identifying degradation causes of lab scale. The short life time of HT-PEMFC is still the problem for its commercialization. In this paper, an operating method to maximize life time of 5kW HT-PEMFC stack are proposed. The proposed method includes major steps such as minimization of OCV (Open Circuit Voltage) exposure, control of the proper stack temperature, and N2 purging for the stack. This long life operating method was based on the fragmentary results of degradation from previous research works. Experimentally, the 5 kW homemade HT-PEMFC stack was operated for a long time based on the proposed method and the stack successfully can operate within the desired degradation rate for the target life time.

• Korean Membrane Journal
• /
• v.9 no.1
• /
• pp.43-51
• /
• 2007

This paper describes the preparation and characterization of two kinds of fluorinated polybenzimidazole (PBI)s which can be potentially used for phosphoric acid-doped, high-temperature polymer electrolyte membrane fuel cells. Two kinds of perfluorocyclobutane (PFCB)-containing monomers were prepared via following synthetic steps; after fluoroalkylation of methyl 3-(hydroxy) benzoate and methyl 4-(hydroxy) benzoate with 1,2-dibromotetrafluoroethane and subsequent Zn-mediated dehalogenation, these compounds were cyclodimerized at $200^{\circ}C$ affording the ester-terminated monomers containing PFCB ether groups. The synthesized intermediates and monomers were characterized using FT-IR, $^1H-NMR,\;^{19}F-NMR$, and mass spectroscopy. The fluorinated PBIs were then successfully prepared through the solution polycondensation of the monomers and 3,3'-diaminobenzidine in polyphosphoric acid. Compared with traditional PBI, the glass transition temperatures of the fluorinated PBIs were obtained at $262^{\circ}C\;and\;269^{\circ}C$ which are lower than that of PBI and their initial degradation temperatures were still high over $400^{\circ}C$ under nitrogen. The fluorinated PBIs showed higher d-spacing values and improved solubility in several organic solvents as well as phosphoric acid, which confirmed they could be good candidates for the high temperature fuel cell membranes.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.2
• /
• pp.118-123
• /
• 2008

For the hydrogen recirculation system of the PEMFC (polymer electrolyte membrane fuel cell), the ejector is useful to improve the efficiency of the fuel cell system. However, conventional ejector does not keep its entrainment ratio good when the various power duties is required by the fuel cell system. In this study, the variable multi-ejector acceptable in the whole duty range required from the fuel cell hybrid mini-bus is developed. Consequently, the performance of the developed ejector is verified by the experiments based on the real operating conditions.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.6
• /
• pp.547-553
• /
• 2015

For commercialization of fuel cell electric vehicles, one of the key objectives is to reduce cost of full stack assembly. Regarding Membrane Electrode Assembly, the major issue is to improve fuel cell activation process in the initial Hydrogen Oxidation Reaction and Oxygen Reduction Reaction. In this research, the VD (Vacuum Drying) process has been developed for improvement of activation process. The VD condition is developed by controlling the temperature and degree of vacuum to remove the remaining solvent of electrode. Consequently, the electrode applied to VD process showed the low characteristics such as 3.5% of remaining solvent content and the improved efficiency such as 15% of activation process speed.

• Membrane Journal
• /
• v.27 no.2
• /
• pp.182-188
• /
• 2017

Sulfonated poly(arylene ether sulfone) (SPAES)-3-mercaptopropyl silica gel (3MPTSG) composite membranes with improved oxidative stability were prepared for polymer electrolyte fuel cell application. It has been reported that ether part of main chain of aromatic hydrocarbon based membranes were weak to radical attack to decrease membrane durability. In this study, the hydrophilic inorganic particles were introduced by minimizing a decrease in ion conductivity and increasing an oxidative stability. The composite membranes were investigated in terms of ionic conductivity, ion exchange capacity (IEC), FT-IR, TGA and contact angle, etc. As a result, increasing amount of the 3MPTSG resulted in decrease in proton conductivities and water uptakes at 100% R.H. but enhanced thermal and oxidative stabilities.

• Applied Chemistry for Engineering
• /
• v.19 no.2
• /
• pp.205-208
• /
• 2008

Sulfonated polySEBS and sulfonated PS were synthesized by sulfonation at the aromatic group of polySEBS and PS. Novel sulfonated polySEBS/sulfonated PS blending films for the ion exchange membrane of polymer electrolyte fuel cell were prepared from these sulfonated polymers. The proton conductivities of these blending films were varied in $10^{-2}{\sim}10^{-3}S/cm$ with the blending ratio of sulfonated polySEBS/sulfonated PS. Especially, the film prepared from the addition of the sulfonated PS (0.5 g) in the sulfonated polySEBS (10.0 g) has the best proton conductivity (0.07 S/cm) with ion exchange capacity (0.75 meq/g) and water uptake (25%).

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.87.1-87.1
• /
• 2010

Metallic bipolar plate is the one of the promising candidate material for PEMFC because of mechanical strength, low gas permeability, electrical and thermal conductivity. However, the corrosion is the main obstacle of metallic bipolar plate, and many investigations, especially coating on base metal, have been carried out to avoid corrosion. Gold is considered as the one of the best coating material because of its corrosion resistance and electrical conductivity. In this study, gold coated metallic bipolar plate was developed and evaluated. Due to our coating process, gold can be well-adhere to the base material, and hydrophobic material on its gold surface was coated by dipping method for better water management. To verify coating reliability, a single fuel cell(50cm2) was evaluated, and its durability over 4000hrs was demonstrated.