• Journal of the Korean Electrochemical Society
• /
• 제11권1호
• /
• pp.11-15
• /
• 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.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.84.2-84.2
• /
• 2011

In this research, two thin film deposition techniques, Atomic Layer Deposition and Sputtering are carried out for the fabrication of Yittria Stabilized Zirconia electrolyte for thin film Solid Oxide Fuel Cell. Zirconium to Yittrium ratio for both cases is about 1/8. Scanning Electron Microscope(SEM) image shows that the growth rate per hour for Atomic Layer Deposition is faster than for sputtering. X-ray Photo-electron Spectroscopy(XPS) shows that the peaks of both Zirconia and Yittria shift towards higher bending energy for the case of Atomic Layer deposition and thus are more strongly attached to the substrate. Later, Nyquist plot was used to compare the conductivity of Yittria Stabilized Electrolyte for both cases. The conductivity at $300^{\circ}C$ for Atomic Layer Deposited Yittria Stabilized Zirconia is found to be $5{\times}10^{-4}S/cm$ while that for sputtered Yittria Stabilized Zirconia is $2{\times}10^{-5}S/cm$ at the same temperature. The reason for better performance for Atomic Layered YSZ is believed to be the Nano-structured layer fabrication that aids in along the plane conduction as compared to the columnarly structured Sputtered YSZ.

• Carbon letters
• /
• 제11권4호
• /
• pp.336-342
• /
• 2010

Different oxidation treatments on CNTs using diluted 4.0 M $H_2SO_4$ solution at room temperature and or at $90^{\circ}C$ reflux conditions were investigated to elucidate the physical and chemical changes occurring on the treated CNTs, which might have significant effects on their performance as catalyst supports in PEM fuel cells. Raman spectroscopy, X-ray diffraction and transmission electron microscope analyses were made for the acid treated CNTs to determine the particle size and distribution of the CNT-supported Pt-Ru nanoparticles. These CNT-supported Pt-based nanoparticles were then employed as anode catalysts in PEMFC to investigate their catalytic activity and single-cell performance towards $H_2$ oxidation. Based on PEMFC performance results, refluxed Pt-Ru/CNT catalysts prepared using CNTs treated at $90^{\circ}C$ for 0.5 h as anode have shown better catalytic activity and PEMFC polarization performance than those of the commercially available Pt-Ru/C catalyst from ETEK and other Pt-Ru/CNT catalysts developed using raw CNT, thus demonstrating the importance of acid treatment in improving and optimizing the surface properties of catalyst support.

• Journal of the Korea Institute of Military Science and Technology
• /
• 제15권4호
• /
• pp.519-526
• /
• 2012

Recently fuel cell is considered to be a new technology that can substitute the ICE(Internal Combustion Engine) as well as overcome environmental issues. In military applications, fuel cell has an unique advantages, which are quietness, namely, stealth. The environmental requirement such as shock and vibration in military application, however, is very severe comparing to civilian demand. Especially, the safety concerning hydrogen storage is the most important problem. Among the candidate methods to store hydrogen, the metal hydride storage is promising method owing to the storage mechanism of chemical absorption of hydrogen to metal hydrides. In this study, the new composition of Ti-Zr type metal hydride(A composition) was suggested and investigated to increase the hydrogen storage capacity. For comparison, the hydrogen charge-discharge properties were investigated with the commercialized Ti-Zr type metal hydride(B composition) using PCT(Pressure-Composition-Temperature) measurement. Also two hydrogen storage cylinders were loaded with each metal hydride and their hydrogen charging and discharging characteristics were investigated. As a result, it was found that the new Ti-Zr type metal hydride has a slightly higher hydrogen storage capacity compared to commercial Ti-Zr type metal hydride.

• Transactions of the Korean hydrogen and new energy society
• /
• 제30권2호
• /
• pp.128-135
• /
• 2019

In this study, the mesoporous $SiO_2$ (5, 10, or 15 wt%) was incorporated into the polybenzimidazole matrix in order to improve the proton conduction as well as physiochemical properties of composite membrane. The chemical structure of mesoporous $SiO_2$ and crystallinity of as-prepared membranes were analyzed by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. The thermal stability of the pristine $X_1Y_9$ and composite membranes were evaluated by thermogravimetric analyzer (TGA). On other side, the physical and chemical properties of the pristine $X_1Y_9$ and composite membranes were also determined by acid uptake and oxidative stability tests, respectively. With the incorporation of 15 wt% $SiO_2$, the composite membrane exhibits the higher proton conductivity that may be applicable for non-humidified high temperature fuel cell applications.

• Journal of Energy Engineering
• /
• 제24권3호
• /
• pp.89-95
• /
• 2015

Carbon felts manufactured by (Co)CNF were subjected to heat treatment under different temperatures to use for the electrode of a redox-flow battery. BET and weight loss were tested to investigate the physical properties of the carbon felt according to the heat treatment conditions. SEM and XPS were also analyzed to characterize their surface area. In addition, electrical resistance, CV (cyclic voltammetry) and RFB charge on the electrode properties were examined in accordance with the heat treatment conditions with the discharge performance. The changes of physical properties on the carbon felt surface was confirmed via SEM and BET analysis, The most addition of oxygen functional groups on the carbon felt surface was obtained when one hour heat treatment at $550^{\circ}C$ and it was confirmed by XPS analysis. After resulting the CV tests, the active area of the electrode was the largest at $550^{\circ}C$ heat treatment. The heat treatment experiment of vanadium redox flow battery using the carbon felts were tested at $400^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$. As a result, the charge-discharge energy efficiency of the heat treatment electrode was 72.9% and 79.8%, at $400^{\circ}C$ and $500^{\circ}C$, respectively. The efficiency of the heat treatment electrode at $550^{\circ}C$ was the best as 79.8% at $550^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 한국소성가공학회 2007년도 추계학술대회 논문집
• /
• pp.296-299
• /
• 2007

The focus of this study is to estimate the stiffness factor of the separator plate of MCFC (Molten Carbonate Fuel Cell) at the elevated temperature. The process factors affecting the stiffness of the separator plate were chosen to determine the most important factor using the finite element analysis with the Taguchi method. The most influential factor, picked out by the ANOYA, turned out the pitch in the separator plate.

• Transactions of the Korean hydrogen and new energy society
• /
• 제16권1호
• /
• pp.82-91
• /
• 2005

Polymer membrane needs to maintain appropriate moisture. Insufficient moisture causes low conduction of hydrogen ion because of increased contact resistance between electrode and membrane by shrinking membrane, and abundant moisture decreases fuel cell performance as difficulty of diffusion reacting gas. Therefore, water controlling system is very consequential for the polymer membrane fuel cell. If hollow fiber membrane humidification is used between fuel and air lines, it is possible to supply heat to fuel and air by using thermal exchanger. It can supply appropriate humidity depending on operating temperature, and can recover heat from exhaust gas which contains water vapor and air. Because of simple structure of humidification system, this system can be easily applied in the PEMFC and cut down cost.

• Journal of Advanced Marine Engineering and Technology
• /
• 제36권2호
• /
• pp.244-249
• /
• 2012

Recently energy crisis and environmental pollution using fossil fuel became social issue. The Fuel Cell, one of the new and renewable energy has great advantage for the former mentioned problems. The PEM Fuel Cell needs highly purified hydrogen for fuel, in many cases CH4 was reformed to H2 basically using steam reforming. The purpose of this paper is to understand the probability of ceramic honeycomb to apply the combustor of STR. We tested the heat accumulation performance of ceramic honeycomb by change of excess air ratio. The results were suitable for our purpose and also these results can be used to make high temperature air at mild combustion field.

• Macromolecular Research
• /
• 제14권4호
• /
• pp.449-455
• /
• 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.