• Title/Summary/Keyword: Ni-MH battery

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Electrode properties upon the substitution of Mo for Mn in Zr-basd AB2-type Hydrogen Storage Alloys (Zr1-xTixV0.4Ni1.2Mn0.4-yMoy계 합금전극의 Mo 함량에 따른 물성 및 전극특성)

  • Seo, Chan-Yeol;Park, Choong-Nyeon
    • Transactions of the Korean hydrogen and new energy society
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    • v.11 no.4
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    • pp.189-202
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    • 2000
  • $AB_2$ type Zr-based Laves phases alloys have been studied for potential application as a negative electrode in a Ni-MH battery. The $AB_2$-type electrodes have a much higher energy density than $AB_5$-type electrodes per weight, however they have some disadvantages such as poor activation behavior and cycle life etc. Nonetheless, the $AB_2$-type electrodes have been studied very extensively due to their high energy density. In this study, in order to develop the cycle life, the Mn of $AB_2$ alloy composition was substituted partially by Mo. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The alloy powder was used below 200-325 mesh for experiments. The structures and phases of the alloys were analyzed by XRD, SEM and EDS, and measured the curve of a pressure-composition isotherms. The electrodes were prepared by cold pressing of the copper-coated(25 wt%) alloy powders, and tested by a half cell. The results are summarized as follows. The cycle life was improved with the increase of Mo amount in $Zr_{1-x}Ti_xV_{0.4}Ni_{1.2}Mn_{0.4}Mo_y$(x=0.3, 0.4) and the activation was faster, whereas the discharge capacity decreased.

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Hydrogenation Study of Mg-based Alloys by mechanical Grinding Reaction for Hydrogen Storage of Fuel Cell (연료전지의 수소저장용 마그네슘계 합금의 기계적 분쇄 반응에 의한 수소화 특성 평가)

  • Kim, Ho-Sung;Suh, Hee-Seok;Cha, Jae-Sang
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.6
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    • pp.69-74
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    • 2006
  • The effects of mechanical grinding(MG) treatment on the hydrogen storage of $Mg_2Ni$ alloy and $Mg_2Ni$ composite alloy($Mg_2Ni+graphite$) were investigated by pressure-composition-temperature(PCT) measurement, the micro-electrode technique of electrochemistry and etc, in which PCT was measured at high temperature(around $300[^{\circ}C]$) of gas phase and a carbon-filament micro-electrode for electrochemical evaluation was manipulated to make electrical contact with the particle in 1M KOH aqueous solution. It was found that the hydrogenation properties of $Mg_2Ni$ and graphite composite particle were greatly improved by the mechanical grinding treatment by which the $Mg_2Ni$ and graphite composite alloys could be changed into microstructure and nano-level particles. namely; the hydrogen dissociation pressure of PCT measurement was decreased from 0.55[MPa] to 0.42[MPa] and hydrogenation peaks by micro-electrode were also observed more clearly on the same sample.

A Study on Metal Hydride Electrode of Ni/MH Battery(I) (니켈/금속수소 축전지의 금속수소 전극에 관한 연구(I))

  • Kim, Jeong-Seon;Cho, Won-Il;Cho, Byung-Won;Yun, Kyung-Suk;Kim, Sang-Ju;Shin, Chee-Burm
    • Applied Chemistry for Engineering
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    • v.5 no.1
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    • pp.81-89
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    • 1994
  • A study on Mm type electrode which is relatively high in electrode capacity and low in material cost was performed to develope high performance nickel-metal hydride battery. The electrode characteristics were investigated by P-C-T, charge-discharge and microencapsulation treatment experiments. The plateau pressure and hydrogen absorption capacity obtained from the P-C-T experiment were 0.4 atm and 310 mAh/g, respectively. The electrode capacity and stability of microencapsulated electrode were improved than those of conductor mixed electrode and the microencapsulation was possible without pretreatment. The electrode capacity of microencapsulated Mm type alloy was 240~250 mAh/g(0.2 C).

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Kinetic Parameter Analysis of Hydrogen Diffusion Reaction for Hydrogen Storage Alloy of Fuel Cell System (연료전지의 수소저장용 합금에 대한 수소확산반응의 속도론적 해석)

  • Kim, Ho-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.2
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    • pp.45-49
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    • 2006
  • Electrochemical hydrogenation/dehydrogenation properties were studied for a single particle of a Mm-based(Mm : minh metal) hydrogen storage alloy($MmNi_{3.55}Co_{0.75}Mn_{0.4}Al_{0.3}$) for fuel cell and Ni-MH batteries. A carbon fiber microelectrode was manipulated to make electrical contact with an alloy particle, and the 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 $10^{-9}\;and\;10^{-10}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process. Compared with the conventional composite film electrodes, the single particle measurements using the microelectrode gave more detailed, true information about the hydrogen storage alloy.

Electrochemical Hydrogenation Behavior of Surface-Treated Mg-based Alloys for Hydrogen Storage of Fuel Cell (연료전지의 수소저장용 마그네슘계 합금의 표면제어에 의한 전기화학적 수소화 거동 연구)

  • Kim, Ho-Sung;Lee, Jong-Ho;Boo, Seong-Jae
    • 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.