• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.317-323
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• 2006

Electric conductive material should be homogeneously mixed with sulfur in sulfur electrode fabrication of lithium/sulfur battery, because sulfur is electric insulator. In this paper electrochemical properties of Li/S battery was studied with various compositions of sulfur electrodes. When content of sulfur changed from 40 wt.% to 80 wt.%, the 60 wt.% sulfur electrode showed the maximum capacity of 1489 mAh/g-sulfur. Electrochemical properties of Li/S battery using 60 wt.% sulfur was also investigated with various carbon contents. The discharge capacity changed as a function of carbon contents. The optimum composition was 25 wt.% carbon for 60 wt.% sulfur electrode.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.92-101
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• 2005

[ $Li_3AlH_6$ ] (5.6wt% theoretical hydrogen storage capacity) powders with and without Ti-containing dopants have been successfully synthesized by mechanochemical reaction near room temperatures from mixtures of LiH and $LiAlH_4$ powders. It has been observed that single phase $Li_3AlH_6$ could be obtained within 2-3 hours of milling, but the addition of reactive $TiCl_2\;or\;TiCl_3$ to the starting mixtures. caused partial decomposition of $LiAlH_4$ into LiCl and free Al with gaseous $H_2$. By addition of these reactive dopants to the as-synthesized $Li_3AlH_6$, this problem could be solved. The addition of 2 mol% $TiCl_2\;or\;TiCl_3\;to\;Li_3AlH_6$ decreased the decomposition start temperature up to 30-50$^{\circ}C$, while that of Ti or $TiH_2$ did not change the thermal decomposition behavior of $Li_3AIH_6$.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.383-387
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• 2012

The activation of Mg-10 wt%$Fe_2O_3$ was completed after one hydriding-dehydriding cycle. Activated Mg-10 wt%$Fe_2O_3$ absorbed 5.54 wt% H for 60 min at 593 K under 12 bar $H_2$, and desorbed 1.04 wt% H for 60 min at 593 K under 1.0 bar $H_2$. The effect of the reactive grinding on the hydriding and dehydriding rates of Mg was weak. The reactive grinding of Mg with $Fe_2O_3$ is believed to increase the $H_2$-sorption rates by facilitating nucleation (by creating defects on the surface of the Mg particles and by the additive), by making cracks on the surface of Mg particles and reducing the particle size of Mg and thus by shortening the diffusion distances of hydrogen atoms. The added $Fe_2O_3$ and the $Fe_2O_3$ pulverized during mechanical grinding are considered to help the particles of magnesium become finer. Hydriding-dehydriding cycling is also considered to increase the $H_2$-sorption rates of Mg by creating defects and cracks and by reducing the particle size of Mg.

• Transactions of the Korean hydrogen and new energy society
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• v.5 no.2
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• pp.73-79
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• 1994

The hydrogenation behavior of Ti-Ni powders prepared by mechanical alloying in a high energy ball mill have been investigated by P-C isotherm curves, DSC(differential scanning calorimetry), X-ray diffractometer, SEM(scanning electron microscope). Amorphous TiNi phase was formed after 10 milling hours. The hydrogen storage capacity gradually decreased as a function of mechanical alloying time. There appears the DSC endothermic peak due to hydrogen evolution of amorphous hydride phase.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.1
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• pp.26-31
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• 2007

Hydrogen has a high potential to be a renewable substitute for fossil fuels, because of its high gravimetric energy density and environment friendliness. In particular, Magnesium have attracted much interest since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve the kinetic is addition of metal oxide. In this paper, the effect of $Fe_2O_3$ concentration on the kinetics of Mg hydrogen absorption reaction was investigated. $MgH_x-Fe_2O_3$ composites have been synthesized by hydrogen induced mechanical alloying. The powder synthesized was characterized by XRD, SEM and simultaneous TG, DSC analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic PCT apparatus. Absorption and desorption kinetics of Mg catalyzed with 5,10 mass% $Fe_2O_3$ are determined at 423, 473, 523, 573, 623K.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.829-833
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• 2012

SNG (synthetic natural gas or substitute natural gas) could contribute greatly toward energy security. In addition, HCNG (or $H_2CNG$) is expected to be used as a fuel gas for internal combustion engines and home appliances because it has extremely low emissions and high thermal efficiency. However, the hydrogen contained in SNG or HCNG can deteriorate the mechanical properties of the materials used in existing natural gas infrastructure. Therefore, it is necessary to investigate the effect of hydrogen on the mechanical properties of such materials so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on the tensile properties of a low-alloy steel used for manufacturing CNG storage vessels was investigated using the so-called hollow tensile specimen technique.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.203-206
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• 2005

The objective of study on composite cylinder for alternative fuel vehicle is to develop safe, efficient, and commercially viable, on-board fuel storage system for the fuel cell vehicle or natural gas vehicle that use highly compressed gaseous fuel such as hydrogen or natural gas. This study presents the whole procedure of development and certification of a type 3 composite cylinder of 207bar service pressure and 70 liter water capacity, which includes design/analysis, processing of filament winding, and validation through various testing and evaluation. Design methods of liner configuration and winding patterns are presented. Three dimensional, nonlinear finite element analysis techniques are used to predict burst pressure and failure mode. Design and analysis techniques are verified through burst and cycling tests. The full qualification test methods and results for validation and certification are presented.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.81-88
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• 2010

Hydrogen energy applications have recognized clean materials and high energy carrier. Accordingly, Hydrogen energy applies for fuel cell by Mg and Mg-based materials. Mg and Mg-based materials are lightweight and low cost materials with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hinder by its high absorption/desorption temperature, and very slow reaction kinetics. Therefore one of the most methods to improve kinetics focused on addition transition metal oxide. Addition to transition metal oxide in $MgH_x$ powder produce $MgH_x$-metal oxide composition by mechanical alloy and it analyze XRD, EDS, TG/DSC, SEM, and PCT. This report considers kinetics by transition metal oxide rate and Hydrogen pressure. In this research, we can see behavior of hydriding/dehydriding profiles by addition catalyst (transition metal oxide). Results of PCI make a excellent showing $MgH_x$-5wt.% Sc2O3 at 623K, $MgH_x$-10wt.% $Sc_2O_3$ at 573K.

• Carbon letters
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• v.8 no.4
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• pp.340-348
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• 2007

• Carbon letters
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• v.8 no.3
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• pp.225-231
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• 2007