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Effects of rapid quenching on structure and cycle stability of La-Mg-Ni-Co type hydrogen storage alloy

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Rare Metals 2006年第Z1期25卷 207-212页

作者： DONG Xiaoping Lü Fanxiu ZHANG Yanghuan YANG Liying FENG Meng WANG Xinlin School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China School of Mateials Inner Mongolia University of Science and Technology Baotou 01401 China School of Material Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China Department of Functional Material Research Central Iron and Steel Research Institute Beijing 100081 China

In order to improve the cycle stability of La-Mg-Ni-Co type alloy electrode, rapid quenching technology was employed. The effects of rapid quenching on the microstructure and cycle stability of the alloy were investigated. The obtained results show that the La2Mg(Ni0.85Co0.15)9M0.1 (M=B, Cr) alloy electrodes are composed of (La, Mg)Ni3 phase, LaNi5 phase and a small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast MB alloy, and the Ni2B phase in the alloy nearly disappears after rapid quenching. Rapid quenching technology can slightly improve the cycling life of the alloy. When the quenching rate increases from 0 m·s-1 (As-cast is defined as quenching rate of 0 m·s-1) to 30 m·s-1, the cycle lives of the MB, MCr alloys enhance from 86 and 87 cycles to 106 and 119 cycles, respectively. On the other hand, the average capacity decay rates of the MB, MCr alloys decrease from 1.7172 and 1.7178 mAh·g-1·cycle-1 to 1.5751 and 1.3060 mAh·g-1·cycle-1 after 86 charge-discharges cycling, respectively.

关键词： rapid quenching La-Mg-Ni-Co type hydrogen storage alloy structure characteristics cycle stability

Effect of annealing treatment on the anti-pulverization and anti-corrosion properties of La_(0.67)Mg_(0.33)Ni_(2.5)Co_(0.5) hydrogen storage alloy

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Journal of Rare Earths 2015年第4期33卷 417-424页

作者：李平张骏翟富强马光徐丽曲选辉 State Key Laboratory for Advanced Metals and Materials Institute for Advanced Materials and Technology University of Science and Technology Beijing Department of Applied Physics EETAC Polytechnic University of CataloniaCastelldefels 08860 Spain State Grid Smart Research Institute

The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy powders after gaseous hydriding and dehydriding cycle was investigated and the discovery was that annealing treatment could hardly ameliorate their anti-pulverization ability. The element content of La, Mg, Ni and Co existing in electrolyte before and after the electrochemical cycles by using ICP-AES technology was also analyzed and it showed that a large amount of La and Mg were dissolved in the electrolyte, but the amount of dissolution for La and Mg significantly declined when the alloy was annealed. The XRD analysis revealed that all the al- loys consisted of two main phases AB3 and AB2 and a residual phase AB5 while annealing treatment made the AB2 phase decrease slightly. Furthermore, the anti-corrosion abilities of various elements in different phases of the as-cast and annealed alloy samples were studied by analyzing the element （La, Mg, Ni, Co） change with the corrosion time in phases AB3 and AB2 by means of EDS. It turned out that the element of La was mainly corroded out from the phase AB2 while not easily from the phase AB3. However, the element of Mg was both easily corroded out from the phases AB2 and AB3, but the corrosion was more obvious in the phase AB3. Therefore, annealing improved the anti-corrosion performances of La and Mg in the phase AB2.

关键词： hydrogen storage alloy La-Mg based metal hydride electrochemical performance cyclical stability rare earths

Effect of rapid solidification treatment on structure and electrochemical performance of low-Co AB5-type hydrogen storage alloy

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Journal of Rare Earths 2014年第6期32卷 526-531页

作者：姚青荣唐莹周怀营邓健秋王仲民潘顺康饶光辉朱其明 School of Materials and Engineering Central South University School of Materials Science and Engineering Guilin University of Electronic Technology Guangxi Key Laboratory of Information Materials Guilin University of Electronic Technology School of Science Guangxi University for Ationalities

The effect of rapid solidification on structure and electrochemical performance of the LaNi4.5Co0.25Al0.25 hydrogen storage alloy was investigated by X-ray powder diffraction and a simulated battery test, including maximum capacity, cycling stability, self-discharge, and high-rate discharge ability （HRD）. All the melt-spun alloys were single-phase with the CaCu5-type structure （space groupP6/mmm）. In comparison to the as-cast alloy, the rapidly quenched alloys manifested an improved homogeneity of com-position and expanded lattice parameters. The electrochemical measurements showed that the activation property, cycling stability and self-discharge of the alloy electrodes were also improved for the rapid solidified alloys. The HRDof the as-cast alloy was better than those of all the rapidly solidified alloys. As the quenching rate increased, the HRD and exchange current density first decreased and then increased.

关键词： hydrogen storage alloy electrochemical properties rapid solidification quenching rate rare earths

Microstructure and electrochemical properties of melt-spun Nd_(0.8)Mg_(0.2)(Ni_(0.8)Co_(0.2))_(3.8) hydrogen storage alloy

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Journal of Rare Earths 2010年第1期28卷 100-103页

作者：潘崇超蔡吴鹏王震耿朝青于荣海 Key Laboratory of Advanced Materials Department of Materials Science and EngineeringTsinghua University

The effects of rapid solidification on the microstructure and electrochemical properties of Nd0.8Mg0.2(Ni0.8Co0.2)3.8 alloy were systematically *** microstructure of alloys was characterized by scanning electron microscopy(SEM),X-ray diffractometer(XRD) and transmission electron microscopy(TEM).It was found that the melt-spun Nd0.8Mg0.2(Ni0.8Co0.2)3.8 ribbons became thinner and the average grain size of the ribbons became smaller with increasing wheel speed.A fraction of amorphous phase was obs...

关键词： hydrogen storage alloy rapid solidification microstructure electrochemical property rare earths

Study on Degradation and Recovery of AB_5-Type hydrogen storage alloy Used in Ni-MH Batteries

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Journal of Rare Earths 2002年第3期20卷 213-217页

作者：王荣阎杰周震周作祥邓斌高学平 Inst. of New Energy Mater. Chem. Nankai Univ. Tianjin 300071 China

The influences of deeply overdischarge on the negative electrode alloy of Ni/MH battery were studied. After overdischarge, La(OH) 3 and Al(OH) 3 are found to form in the negative electrode through XRD analysis. The hydrogen storage alloy powder from spent Ni/MH batteries was recovered by chemical and melting method according to degradation mechanism. The structure of recovered alloy was measured by XRD. The experimental results demonstrate that the alloy structure is CaCu 5 type. The constant current charge/discharge test was carried out to the original alloy and the recovered alloy. It is found that their discharge capacities are almost the same, but the discharge potential of the recovered alloy is higher than that of the original alloy. The results of cyclic lifetime test demonstrate that the capacity degradation of the recovered alloy is slower than that of the original one.

关键词： rare earths Ni/MH battery overdischarge hydrogen storage alloy recovery

Effect of Ambient Temperature on the Electrochemical Properties of La_4MgNi_(17.5)Co_(1.5) hydrogen storage alloy

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Acta Metallurgica Sinica(English Letters) 2016年第7期29卷 614-618页

作者： Xin Cai Fan-Song Wei Fan-Na Wei Huan-Huan Lu Department of Material Science and Engineering Jiangsu University of Science and Technology

The effect of different ambient temperatures on the electrochemical properties of La4MgNi17.5C01.5 hydrogen storage alloy was investigated. The X-ray diffraction pattern shows that the alloy consists of LaNis-type phase and AsB19- type （Ce5C019 ＋ Pr5CO19） phase. With the increase of the ambient temperature, the maximum discharge capacity of the alloy electrodes increases from 353.33 （283 K） to 379.25 mAh/g （308 K）, and the cyclic stability （Sloo） of the electrodes decreases from 80.19 （283 K） to 52.04% （308 K） due to the acceleration of pulverization, corrosion and oxidation at higher ambient temperature. Moreover, it is found that the increase of the temperature can accelerate the diffusion rate of hydrogen in the alloy （D） and increase the exchange current density （Io）, which are beneficial for improving the activation performance and the high-rate dischargeability （HRD） of the alloy electrodes. The activation cycles of the electrodes decrease from 4 （283 K） to 1 （308 K）, and the HRD9oo of the electrodes sharply increases from 66.36 （283 K） to 95.64% （308 K）.

关键词： hydrogen storage alloy Ambient temperature AsB19 type Electrochemical property

Process optimization of electroless copper plating and its influence on electrochemical properties of AB_5-type hydrogen storage alloy

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Journal of Rare Earths 2010年第6期28卷 922-926页

作者：张博吴文远尹少华李世伟罗瑶边雪涂赣峰 School of Materials & Metallurgy Northeastern University

The amount of Cu coating by chemical plating was investigated based on quadratic regression orthogonal experimental design being adapted to the variation law of temperature, pH value and Ni2+ concentration, and the relevant regression equation was expressed as y=2.1609+0.5295×10-3T2-0.0342P2-0.0265N2+0.0023TP+0.0020TH+0.0199PN-0.0959T+0.3814P-0.2073N. The results showed that the deposition rate augmented with the increasing in temperature, pH value and Ni2+ concentration. The experimental parameters of the optimal coating were temperature 75 °C, pH value 8.5 and Ni2+ concentration 1.2 g/L. The electrochemical tests indicated that the cycle stability increased from 60.66% to 75.58%, indicating that the treated alloy exhibited better corrosion resistance.

关键词： hydrogen storage alloy electroless copper plating electrochemical performance rare earths

EFFECT OF ANNEALING ON THE ELECTRODE PERFORMANCESOF ZrTi(MnVCoNi)_2 hydrogen storage alloy

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Acta Metallurgica Sinica(English Letters) 1999年第6期12卷 0-0,0-0+0-0页

作者： X.G, Yang Q.A. Zhang K. Y Shu YL. Du YQ. Lei and Q.D. Wang (Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China )W.K. Zhang(Department of Applied Chemistry, Zhejiang University of Technology, Hangzhou 3100l4, C

The annealing treatment was found to improve the cyclic stability but to degmde discharpe capacity, activation and high-rate discharpeability for the Ti-substituted AB2type alloy electrode. A larper polarization was found in the annealed alloy because of its poor discharpe kinetics resulted hem the structural homogeneity. At larae discharpe cumnts, the hydmpen dchsion in the bulk of the alloy was mpaofed as the mte-determining step. Based on the P ressure-composition isotherm measurement, we concluded that the decrease in discharpeability of the annealed alloy is owing to the low and flat pressure plateau, as well as the large hysteresis, but the hydrgen stomge density almost remains unchangeable after annealing.

关键词： AB_2 hydrogen storage alloy annealing electrochemical property homogeneity P-C-T

Low-Temperature hydrogen storage alloy and Its Application in Ni-MH Battery

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Journal of Rare Earths 2004年第6期22卷 882-886页

作者：陶明大陈云贵吴朝玲付春艳涂铭旌 School of Materials Science and Engineering Sichuan University Chengdu 610064China

Rare earth compositions, La, Ce and Pr in Mm(NiCoMnAl)(5) hydrogen storage alloy, were arranged by uniform design method. The discharge performances and kinetics parameters including capacity, exchange current density, symmetry factor and hydrogen diffusion coefficient of the alloy at -40degreesC, were tested in standard tri-electrode cell. And linear regression method was used to analyze the effect of rare earth compositions on the performances of hydrogen storage alloys. The results show that the capacities of the alloys are positively correlative to the square of Ce content at -40degreesC and under both 0.4 and 0.2C rate. The kinetics parameters and hydrogen diffusion coefficient indicate that the low-temperature performances of the alloys are mainly controlled by hydrogen diffusion process, and the surface electrochemical reaction affects the low-temperature performances to a certain extent. The low-temperature discharge capacities of the battery were also tested. The results show excellent low-temperature performances. The battery delivers 69.6% of its room-temperature capacity at -40degreesC and 0.2C rate, 77.7% at -40degreesC and 0.4C rate, 59.1% at -45degreesC and 0.2C rate.

关键词： hydrogen storage alloy low-temperature performances aggression analysis Ni-MH battery rare earths