• Journal of Hydrogen and New Energy
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• v.6 no.2
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• pp.65-73
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• 1995

Negative electrode was prepared by mixing $Ti_{0.7}Zr_{0.3}Cr_{0.3}Mn_{0.3}V_{0.6}Ni_{0.8}$ alloy powder with copper or nickel powder and pressing in the air. The cycled electrodes were analyzed with SEM, potentiostat and electrochemical impedance spectroscopy. It was found that the Cu-compacted electrode showed better low temperature dischargeability and higher rate capability than Ni-compacted electrode. From SEM analysis of the cycled electrode compacted with copper powder, it was observed that the surface of MH particles was covered with copper grains and whisker precipitated from electrolyte after dissolution during cell test. It is found that the improved electrode characteristics are attributed to the copper layer on MH particles deposited by dissolution and precipitation(DP) process.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.43-46
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• 2007

To find out the optimum design of hydrogen storage and supply tank using Metal Hydride (briefly MH) and to make clear the performance characteristics under various conditions are our research purpose. In order to use the low-temperature exhaust heat, $LaNi_{4.7}Al_{0.3}$ which operates under the low pressure of 1MPa is chosen, and we measure the basic properties, namely density, specific heat, PCT(Pressure-Concentration-Temperature) characteristic, and effective thermal conductivity. Then, a numerical calculation model of hydrogen storage using MH alloy is suggested and this thermal diffusion equation of model is solved by the backward difference method. This calculation results rate compared with the experimental results of the systems which installed 1kg MH alloy and, it is found out that our calculation model can well predict the experimental results. By the experimental using MH alloy, it is recognized that the hydrogen flow rate can control by the step adjustment of brine temperature.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.464-466
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• 1993

In this paper, a peak detection algorithm having high reliability is proposed. The peak detection algorithm is implemented to a charger and power control system which is applicable to home appliances or notebook PC directly. The charger and power control system is controlled by a microprocessor, M50927 (Mitzubishi), to improve cost to performance ratio. The charger algorithm is designed to be operated under optimal charge node and various protections are added tn improve the reliability of the charger.

• Journal of Hydrogen and New Energy
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• v.9 no.1
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• pp.16-24
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• 1998

Recently Zr-based $AB_2$ type hydrogen absorbing alloy has received much attention as a negative electrode material for the Ni-MH batteries because of its high capacity. In this study $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy was chosen and the effects of heat treatment and a partial substitution of the Mo in Mn site on the various electrode properties were investigated. The alloys was prepared by arc melting (as-cast sample). Some of them were heat treated at $1,100^{\circ}C$ for 4 hours. After this they were differentiated by the different cooling rates of slow cooling and quenching. Various electrode characteristics such as activation process, high rate dischargeability and self discharge characteristic were investigated with the three types of electrodes. It was found that heat treated alloys resulted in an increase in plateau flatness of P-C isotherms however both discharge capacity and high rate capability were decreased. And the partial substitution of Mo for Mn in $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy improved the self-discharge characteristic without the loss of discharge capacity (300mAh/g).

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1509-1511
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• 2005

군수용 이차전지는 납축전지, 니켈-카드뮴전지 등이 주로 응용되고 있다. 군수용 전지의 경우 민수용에 비해 사용온도범위가 넓고, 진동, 충격 등의 환경시험규격이 까다로우며, 높은 신뢰성이 보장되어야만 한다. 또한 최근 환경문제의 부각으로 니켈-카드뮴전지는 차츰 설자리를 잃어가고 있으며, 납축전지의 경우 오염물질의 배출뿐만 아니라 저온성능이 떨어지는 단점을 가지고 있다. 이의 일환으로 최근 선진외국에서는 이를 대체하기 위한 연료전지, 리튬-이온, 리튬-폴리머, 니켈-수소전지 등의 개발 및 적용이 확대되고 있는 실정이다. 하지만 연료전지의 경우 상용화가 아직 이루어지지 않고 있으며, 리튬계열 배터리의 경우 이상상태에서 폭발하는 특성을 갖고 있어 많은 문제점을 내포하고 있다. 본 논문에서는 군용 니켈-수소전지를 대상으로 특성을 알아보고 배터리의 합리적 운용을 돕기 위한 배터리관리시스템에 대해 살펴보고자 한다.

• 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.13 no.3
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• pp.190-196
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• 2002

Ni/MH 박막전지의 전극으로 사용될 수 $Mg_{2}Ni$박막을 스퍼터링방법으로 제조하였다. $Mg_{2}Ni$합금박막은 Mg, Ni타?을 이용하여 동시에 스퍼터링함으로서 제조하였다. KOH 액체전해질 및 $Ni(OH)_2$전극을 이용하여 전기화학실험을 하였다. $Mg_2Ni$ 박막의 초기 싸이클 특성에 미치는 열처리 효과를 조사하기 위하여, $200-550^{\circ}C$로 변화시키면서 진공중에서 열처리를 하였다. 열처리온도가 $300^{\circ}C$ 이하에서는 초기방전용량이 증가하였으며, $400^{\circ}C$ 열처리시에는 활성화시의 방전용량이 약 160mAh/g으로 가장 크게 나타났다.

• Journal of Hydrogen and New Energy
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• v.10 no.3
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• pp.185-189
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• 1999

Effects of alloy modification with the $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy for an electrode use have been investigated. For the alloy composition, a part of Mn was substituted by Co, Cr and Fe. The experimental results showed that Co accelerated activation of alloy, and Fe and Cr improved the discharge capacity. These results agree with P-C-T curves of each alloy. But substituting Fe for Mn showed the decrease of the discharge capacity when discharged at high rate (60mA, about 1C rate). Considering both the discharge capacity and the high rate discharge property, $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$ alloy was found to be the best alloy among the alloys subjected to the test.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.294-299
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• 2001

Effects of the surface fluorination on the electrochemical charge-discharge properties of $Mg_2$Ni electrode in Ni-MH batteries fabricated by mechanical alloying were investigated. After 20h ball milling, Mg and Ni powder formed nanocrystalline $Mg_2$Ni. Discharge capacity of this alloy increased greatly at first one cycle, but due to the formation of Mg(OH)$_2$ passive layer, it showed a rapid degradation in alkaline solution within 10cyc1es. In case of 6N KOH +xN KF electrolyte (x = 0.5, 1, 2), a continuous and stable fluorinated layer formed by adding excess F$^{[-10]}$ ion, increased durability of $Mg_2$Ni electrode greatly and high rate discharge capability(90-100mAh/g). 2N KF addition led to the highest durability of all tested here. The reason of the improvement is due to thin MgF$_2$, which can prevent the $Mg_2$Ni electrode from forming Mg(OH)$_2$layer that is the main cause of degradation.

• Journal of Hydrogen and New Energy
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• v.7 no.2
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• pp.137-145
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• 1996

The Zr-based $AB_2$ type Laves phase hydrogen storage alloys have some promising properties, long cycle life, high discharge capacity, as electrode materials in reversible metal hydride batteries. However, when these alloys are used as negative electrode for battery, there is a problem that their rate capabilities are worse than those of commercialized $AB_5$ type hydrogen storage alloys. In this work, we tried to develop the Zr-based $AB_2$ type Laves phase hydrogen storage alloys which have high capacity and, especially, high rate capability.