• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.95-99
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• 2006

Electrochemical properties were studied for a single particle of active material of hydrogen storage alloy $(MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3})$ and nickel hydroxides $(NiOH)_2$ for the secondary Nickel Metal Hydride (Ni-MH) batteries using the microelectrode, which was manipulated to make electrical contact with an active material particle for cyclic voltammograms (CV) and potential-step experiments. As a result of CV test, it was found that three kinds of hydrogen oxidation peaks at -0.9, -0.75 and -0.65 V and hydrogen evolution peak at -0.98 V for hydrogen storage alloy were separately observed and two kinds of peaks of proton oxidation/reduction at 0.45 and 0.32 V and oxygen evolution reaction (OER) at 0.6 V for nickel hydroxides were also more clearly observed. Furthermore hydrogen diffusion coefficient within a single particle was also found to vary the order between $10^{-9}\;and\;10^{-10}cm^2/s$ over the course of hydrogenation and dehydrogenation process for potential-step experiments.

• Journal of Hydrogen and New Energy
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• v.18 no.4
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• pp.399-405
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• 2007

The hyper-eutectic Mg-33.5%Ni alloy was rapidly solidified by melt spinning process. The melt-spun Mg-33.5%Ni has amorphous structure and crystallization occurred above $162^{\circ}C$. The hydriding and dehydriding rates of melt-spun Mg-33.5%Ni increased with cycle and high rate of hydrogen storage occurred at 3rd cycle. The maximum hydrogen amount absorbed in melt-spun Mg-33.5%Ni at $300^{\circ}C$ is about 4.5%.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.263-273
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• 1994

Titanium powder prepared by dehydrogenating the titanium hydride which is synthesized by reacting Ti-sponge (99.67%) with hydrogen using the self-propagating high-temperature synthesis method. In the synthesis of titanium hydride, the particle size of the product was found dependent on the amount of hydrogen incorporated into the titanium such that the particle size of titanium hydride decreased with increasing hydrogen pressure and after-burn time. In the dehydrogenation process, as the dehydrogenation time increase, the particle size of titanium powder increased due to partial melting and sintering of titanium particles.

• Journal of Hydrogen and New Energy
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• v.5 no.1
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• pp.9-17
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• 1994

Activation behavior, hydriding rate and disintegration were studied for a compact in pellet form and hydrogen storage alloy particles treated with newly developed inorganic solution. Cylindrical disc of 12.95mm diameter and of 7.1mm thickness was prepared by compressing(8ton) a mixture of $MmNi_{4.5}Al_{0.47}$ and PTFE. Chemical treatment of particles with 1mol of solution was performed at room temperature for several hours until the pH of solution did not change. Chemical treatment made much accelerated activation without any incubation period which generally exists in the untreated alloys and the hydriding reaction rate after full activation also was improved.

• Journal of Hydrogen and New Energy
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• v.17 no.2
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• pp.174-180
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• 2006

The eutectic Mg-23.5%Ni alloy was casted by melting and solidification. The powders of Mg-23.5%Ni and (Mg-23.5%Ni)-10% iron oxide were prepared by mechanical grinding of casted Mg-Ni alloy and casted Mg-Ni alloy+oxide, respectively. As milling time increases, hydriding and dehydriding rates of Mg-Ni and Mg-Ni-oxide alloy powders increase. The additions of iron oxide to Mg-Ni alloy and Mg-Ni-oxide increase hydriding rates and slightly decrease dehydriding rates.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.46-52
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• 2006

The effects of surface treatment on the hydrogen storage properties of a $Mg_2Ni$ alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle in a KOH aqueous solution. It was found that the hydrogen storage properties of $Mg_2Ni$ at room temperature were improved by the surface treatment with a nickel plating solution. The sodium salts(sodium phosphate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen charge/discharge capacity at room temperature as high as about 150[mAh/g] from the original value of 17[mAh/g]. Potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-8}{\sim}10^{-9}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process.

• Journal of Hydrogen and New Energy
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• v.26 no.6
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• pp.541-546
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• 2015

Global energy shortage problem is expected to increase driven by strong energy demand growth from developing countries. Nuclear fusion power offers the prospect of an almost infinite source of energy for future generations. Hydrogen isotope storage and delivery system is a important subsystem of a nuclear fusion fuel cycle. Metal hydride is a method of the high-density storage of hydrogen isotope. For the safety storage of hydrogen isotope, depleted uranium (DU) has been widely proposed. But DU needs a safe test because It is a radioactive substance. The authors studied a small-scale DU bed and a medium-scale DU bed for the safety test. And then we made a large-scale DU bed and stored hydrogen isotopes in the bed. Before the hydriding/dehydriding, we tested it's heating and cooling properties and carried out an activation procedure. As a result, Reaction rate of DU-$H_2$ is more rapid than the other metal hydride ZrCo. Through the successful storage result of our large bed, the development possibility of the hydrogen isotope storage technology seems promising.