快淬对MlNi3.55Co0.75Mn0.4Al0.3/5wt% Mg2Ni复合储氢合金电化学性能的影响

引用本文

田晓, 特古斯, 海山, 姚占全. 快淬对MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni复合储氢合金电化学性能的影响 . 无机材料学报, 2012, 27(11): 1179-1184[TIAN Xiao, Tegus O, HAI Shan, YAO Zhan-Quan. Effects of Rapid Quenching on Electrochemical Properties of MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni Composite Hydrogen Storage Alloy . Journal of Inorganic Materials, 2012, 27(11): 1179-1184] 复制到剪切板

Permissions

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

快淬对MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni复合储氢合金电化学性能的影响

田晓¹, 特古斯¹, 海山¹, 姚占全²

1.内蒙古师范大学物理与电子信息学院, 功能材料物理与化学自治区重点实验室, 呼和浩特 010022

2.内蒙古农业大学水利与土木建筑工程学院, 呼和浩特 010018

田晓(1972-), 女, 博士, 讲师. E-mail:nsdtx@126.com

基金:内蒙古自然科学基金(2010MS0804); 内蒙古自治区高等学校科学研究基金(NJZY11036); 内蒙古师范大学科研基金(ZRYB09007); 国家自然科学基金(10947008);

中图分类号:TG139 文献标志码:A 文章编号:1000-324X(2012)11-1179-06

Effects of Rapid Quenching on Electrochemical Properties of MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni Composite Hydrogen Storage Alloy

TIAN Xiao¹, Tegus O¹, HAI Shan¹, YAO Zhan-Quan²

1. Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, School of Physics and Electronic Information, Inner Mongolia Normal University, Huhhot 010022, China

2. School of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Huhhot 010018, China

Fund:Natural Science Foundation of Inner Mongolia Autonomous Region (2010MS0804); Science Research Foundation of the Higher Education Institutions of Inner Mongolia Autonomous Region (NJZY11036); Science Research Foundation of Inner Mongolia Normal University (ZRYB09007); National Natural Science Foundation of China (10947008);

Abstract

In order to improve the discharge capacity and the cycling stability of AB₅-type hydrogen storage alloy, the effects of rapid quenching rate on the microstructures and electrochemical properties of MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni composite alloy were investigated by means of inductively coupled plasma (ICP), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometry (EDS), transmission electron microscope (TEM) and electrochemical measurements. The results show that the as-cast composite alloy is composed of the LaNi₅ phase and a small amount of the Mg₂Ni phase. However, the quenched composite alloys consist of the (La,Mg)Ni₃ new phase and the LaNi₅ phase. When the rapid quenching rate is higher than 15 m/s, nanocrystalline structure are formed and partial amorphous structure appeares in the composite alloys. Electrochemical studies show that the maximum discharge capacity and the capacity retention of quenched composite alloys increase firstly and then decrease with increasing rapid quenching rate. The maximum discharge capacity and the capacity retention after 100 cycles of the quenched composite alloy at 20 m/s is up to 344 mAh/g and 93.9%, respectively.

Keyword: rapid quenching; composite hydrogen storage alloy; microstructure; electrochemical properties

Show Figures

就综合性能而言, AB₅ 型储氢合金仍是金属氢化物/镍(MH/Ni)电池的主要负极材料^{[ 1]}. 然而, AB₅型储氢合金由于CaCu₅型晶体结构的限制, 其放电容量一般只有320~340 mAh/g; 并且Co元素的使用, 使合金的成本居高不下, 越来越无法适应现代市场的要求^{[ 2]}. 因此, 迫切需要在AB₅型储氢合金的基础上开发出性价比更高的储氢合金来满足MH/Ni电池的发展需要.

为此, 国际上主要从两方面开展研究: 一是通过合金成分优化或合金微结构改变来改善AB₅型合金的性能^{[ 3, 4, 5, 6, 7]}, 相关研究取得了很大进展, 继续这方面的研究对于储氢性能提升的力度已经很小; 二是通过与其他类型的储氢合金有机复合, 达到优点互补以克服单一合金的固有缺点. 近年来, 国内外研究者在复合合金的类型、组元含量、制备工艺等方面开展了一些相关研究^{[ 8, 9, 10, 11]}. 为了获得优异综合性能、低成本的复合储氢合金, 仍需从多方面进行探索研究.

前期, Liu等^{[ 10]}采用二步熔炼法将难活化、高容量、低廉价格的Mg₂Ni储氢合金与易活化、低容量、高成本的AB₅型储氢合金进行复合. 结果表明, Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni复合储氢合金的活化性能和最大放电容量好于单一AB₅型储氢合金, 但性能改善的幅度比较有限. 这是由于二步熔炼法仅使合金简单机械复合, 两种合金并没有在微观上相互作用, 从而促进性能的提高.

真空快淬工艺是一种通过控制冷却速度的快速凝固非平衡合金制备方法, 可以快速地改变合金的微结构, 使合金获得纳米晶、非晶和微晶等亚稳态结构^{[ 12, 13]}. 由此本工作对二步熔炼法获得的铸态MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni合金在不同快淬速度下进行快淬处理, 并系统研究快淬速度对MlNi_3.55Co_0.75Mn_0.4Al_0.3/5wt% Mg₂Ni复合合金结构和电化学性能的影响.

1 实验

1.1 储氢合金及储氢合金电极制备

实验所用原料Ml的化学组成为: 80.6wt% 镧, 8.4wt%铈、5.7wt%镨和5.3wt%钕, 其余金属(Ni, Co, Mn, Al, Mg)的纯度均高于99.8%. 在氩气保护下, 合金MlNi_3.55Co_0.75Mn_0.4Al_0.3 (以下简称AB₅)采用磁悬浮高频感应炉熔炼, Mg₂Ni合金采用真空中频感应炉熔炼, 适当考虑稀土和金属Mg的烧损. 然后, 按AB₅/5wt% Mg₂Ni组成将两种合金混合, 采用磁悬浮高频感应炉在氩气保护下重熔制备铸态复合合金. 最后, 采用真空快淬设备将部分铸态复合合金再次重熔进行单辊快淬处理, 最终获得快淬态合金. 快淬速度以冷凝铜辊的表面线速度来表示, 本试验分别采用0、15、20、25和30 m/s的快淬速度, 相应的快淬态合金分别以R0 (铸态)、R15、R20、R25和R30表示. 合金研磨成粉后过65 µm筛用于结构和电化学性能测试.

将合金粉与羰基镍粉按1:3的比例均匀混合, 称取1 g合金粉和羟基镍粉的混合物装入特制的钢模具中, 在20 MPa的压力下保压20 min压制成φ15 mm的圆电极片, 然后用泡沫镍片包覆圆电极片, 用点焊机将泡沫镍片周围点焊固定, 并点焊镍带作为镍电极引线.

1.2 合金结构表征及电化学性能测试

合金成分组成采用OPTIMA 7300V 型电感耦合等离子发射光谱仪(ICP)进行分析. 合金的相组成和结构分析方法及采用的仪器参见文献[14].

采用恒电流充放电方式在LAND CT2001A电池测试仪(武汉金诺生产)上进行电化学性能测试. 合金电极的活化性能和循环稳定性充放电制度参见文献^{[ 15]}.

2 结果与讨论

2.1 合金的相结构与微观组织

表1是AB₅/5wt% Mg₂Ni复合合金成分的ICP 测试结果, 由表1可见, R0复合合金的实际成分组成及含量与合金设计成分组成及含量基本接近. R0实际组成成分中稀土元素和Mg元素比设计成分稍高一些, 正如前面所述, 这是由于适当考虑稀土和金属Mg的烧损时, 添加过量所致. 此外, 与R0复合合金的实际成分组成及含量相比, 快淬态复合合金中除Ni元素之外, 其他元素含量均稍有所下降, 可能是快淬重熔烧损所致.

表1 AB₅/5wt% Mg₂Ni复合合金成分的ICP测试结果 Table 1 ICP analysis result of the AB₅/5wt% Mg₂Ni composite alloys

图1为AB₅合金和经不同快淬速度处理后AB₅/5wt% Mg₂Ni复合合金的XRD图谱. 由图1可知, 铸态AB₅合金由单一CaCu₅型六方结构的LaNi₅相组成. 与铸态AB₅合金相比, R0复合合金中LaNi₅相的大部分衍射峰强度明显变弱, 并伴有部分衍射峰消失, 但在2 θ=44.9°和2 θ=69.2°位置的衍射峰强度明显增强, 这可能是与Mg₂Ni相的衍射峰复合叠加的结果. 因为Mg₂Ni相的(203)主峰就在2 θ=44.9°位置处, 而其(216)衍射峰在2 θ=69.5°位置处. 可以推断, R0复合合金由LaNi₅相和少量的Mg₂Ni相组成.

	Figure Option View Download New Window
	图1 AB₅合金和快淬前后复合合金的XRD图谱Fig. 1 XRD patterns of the AB₅ and rapid quenched AB₅/5wt% Mg₂Ni composite alloys

AB₅/5wt% Mg₂Ni复合合金经快淬处理后发现, 快淬态复合合金由PuNi₃型菱方结构的LaNi₃新相和LaNi₅相组成(图1). 与铸态复合合金R0相比, 除R20快淬态合金中有衍射峰强度明显减小的LaNi₅相衍射峰外, 其他快淬态复合合金中的LaNi₅相衍射峰几乎趋于消失, 这主要是由于快淬导致合金晶粒细化、晶格畸变和非晶结构形成所致. 而快淬态合金中新相LaNi₃衍射峰强度却随快淬速度的增大先增强后减弱, R20合金中的LaNi₃衍射峰最强. 可以推断, 除R20快淬态合金中有一定比例的LaNi₃和LaNi₅相以晶态形式存在外, 其他快淬态复合合金中LaNi₃相主要以晶态存在, 而LaNi₅相却以非晶结构存在.

同一快淬态复合合金中LaNi₅相主要以非晶态结构存在, 而LaNi₃相仍以晶态组织结构存在, 分析认为这是由复合合金中各相结晶过程中过冷度所决定的. 一般而言, 金属结晶过程中的过冷度△ T可以表示^{[ 16]}为:

△ T = T_m - T_n (1)

式中 T_m是金属理论结晶温度, 即金属的熔点; T_n是金属实际结晶温度. 结晶过程中的过冷度越大, 液态金属越不易结晶. 本研究中, 快淬速度的大小代表了合金冷却速度的大小. 快淬速度越大, 合金的冷却速度也越大, 很容易达到合金实际要结晶的温度. 复合合金中由于各相的理论结晶温度(熔点)的不同, 造成过冷度不同. LaNi₅相的熔点大约在 1350℃, LaNi₃相的熔点大约在811℃, 在相同的快淬速度下, LaNi₅相的过冷度明显大于LaNi₃相的过冷度. 因而, LaNi₅相不易结晶形成了非晶相, 而LaNi₃相却结晶形成晶态.

图2为15 m/s快淬速度下AB₅ /5wt% Mg₂Ni复合合金薄带自由面的SEM照片, 合金的化学成分经EDS分析后列于表2. 由SEM照片可以看出快淬态复合合金由两相组成, 深色粗大的树枝晶组织构成连续的基体, 在基体表面零星的分布着明亮的白色小颗粒状组织. 对深色基体组织经EDS分析(表2)表明, 成分中仅包含了AB₅合金的组成元素, 没有Mg元素的存在, 且原子比基本符合AB₅合金的比例, 表明深色基体组织是LaNi₅相; 对明亮的白色小颗粒组织经EDS分析(表2)发现, Mg元素和稀土元素同时存在, 结合ICP和XRD分析认为这是形成了富稀土相(La,Mg)Ni₃.

	Figure Option View Download New Window
	图2 15 m/s快淬速度下AB₅/5wt% Mg₂Ni复合合金薄带自由面的SEM照片Fig. 2 SEM micrograph of AB₅/5wt% Mg₂Ni composite alloy rapidly quenched at 15 m/s

表2 15 m/s快淬速度下AB₅/5wt% Mg₂Ni复合合金的EDS能谱分析结果 Table 2 EDS results of AB₅/5wt% Mg₂Ni composite rapidly quenched at 15 m/s

图3为不同快淬速度下AB₅/5wt% Mg₂Ni复合合金组织的HRTEM照片及选区电子衍射(SAED). 由图3表明, 随着快淬速度的增大, 复合材料颗粒微观组织的晶态由粗大的晶粒逐渐转变为细小的纳米晶, 同时伴有部分非晶化倾向. 结合前面XRD图谱和EDS能谱分析认为, 纳米晶主要是(La,Mg)Ni₃相, 而非晶结构主要是LaNi₅相.

	Figure Option View Download New Window
	图3 快淬态AB₅/5wt% Mg₂Ni复合合金的HRTEM照片(a~d)和SAED分析(a~d插图)Fig. 3 HRTEM micrographs(a-d) and SAED patterns (inset of (a-d)) of AB₅/5wt% Mg₂Ni composite rapidly quenched at (a) 15 m/s; (b) 20 m/s; (c) 25 m/s; (d) 30 m/s

2.2 合金的电化学性能

图4为AB₅合金和经不同快淬速度处理后AB₅/5wt% Mg₂Ni复合合金的活化性能曲线, 其主要电化学性能参数如表3所示. 由图4和表3可见, 所有合金都具有极好的活化性能, 只需1~2次循环即可活化. 与AB₅合金相比, 铸态AB₅/5wt% Mg₂Ni复合合金的放电容量有所增加, 但增加的幅度很有限, 仅仅增加了4 mAh/g. 可见, 将高理论容量的Mg₂Ni合金和AB₅型合金通过简单重熔复合并提高合金的容量很有限. 而AB₅/5wt% Mg₂Ni复合合金经快淬处理后, 合金的容量得到了明显的提高. 由图4及表3可以看出, 随快淬速度的增大, 快淬态复合合金的最大放电容量呈现出先大幅度增加后减少的变化规律, 其中快淬速度为20 m/s时合金电极的放电容量达最大值344 mAh/g. 可见, 快淬处理对复合合金的最大放电容量有明显的影响.

	Figure Option View Download New Window
	图4 AB₅合金和快淬前后复合合金的活化性能曲线Fig. 4 Activation property curves of the AB₅ and rapidly quenched AB₅/5wt% Mg₂Ni composite alloys

表3 合金的活化次数( N _a)、最大放电容量( C_max)、经100次循环后的放电容量( C₁₀₀)和容量保持率( S₁₀₀) Table 3 Activation number ( N_a), the maximum discharge capacity ( C_max), discharge capacity ( C₁₀₀) and capacity retention ( S₁₀₀) after 100 cycles of the alloys

快淬对合金最大放电容量的影响与快淬导致合金的微结构变化有密切关系. 与铸态复合合金R0相比, 快淬态复合合金R15和R20的最大放电容量分别增加了20 mAh/g和28 mAh/g. 分析认为, 容量增大的原因主要由于: (1) 快淬使合金形成(La,Mg)Ni₃新相. 研究表明^{[ 17]}, LaNi₃相的储氢量远高于LaNi₅相. (2) (La,Mg)Ni₃和LaNi₅相按一定比例以晶态结构存在于合金中, 例如R20快淬态合金. 晶态的LaNi₅相在合金中具有双重作用, 一方面起着吸氢作用, 另一方面由于含有高Ni含量对自身以及其它吸氢相(例如(La,Mg)Ni₃相)的电化学反应起着催化作用^{[ 18]}. 因此, 合金中晶态LaNi₅相含量的多少直接决定着(La,Mg)Ni₃相吸氢利用率. (3) 合金晶粒细化也有利于储氢容量的提高^{[ 19]}. 快淬速度大于20 m/s复合合金的容量随快淬速度的增大而逐渐减小, R30的最大放电容量仅为308 mAh/g. 容量减小的主要原因是合金中形成的非晶相随快淬速度的增大而逐渐增多, 因为非晶相的储氢容量只有其晶态的一半左右^{[ 20]}. 正如前面TEM分析结果所述, 快淬速度为30 m/s时, 合金主要是非晶结构.

表3中容量保持率数据表明, 与AB₅合金相比, R0复合合金的容量保持率增加了3.4 %. 这是由于复合合金中Mg₂Ni相与LaNi₅相紧密结合抑制了AB₅合金粉化的结果. 而快淬态复合合金的容量保持率随快淬速度的增大先增大后减小, R20快淬态合金的循环稳定性最好, 经100次充放电循环后, 其容量保持率为93.9%. 可见, 恰当的快淬处理可以明显改善合金的循环稳定性.

研究表明^{[ 21, 22]}, 在储氢合金充放电循环过程中, 导致合金循环稳定性下降的因素有3种: 一是合金的粉化; 二是合金颗粒氧化腐蚀及分凝; 三是不可逆氢化. 三种因素又可以合并为二个方面: 前两种因素是导致合金活性物质总量减少而最终导致合金容量衰退; 第三种因素是导致合金活性物质利用率减少而最终导致合金容量衰退. 因此, 改善合金循环稳定性要从这两方面入手.

本研究中容量保持率随快淬速度的增大得以改善主要归因于快淬导致复合合金中合金晶粒尺寸减小, 合金晶粒的强度和韧性增强, 合金越不易粉化^{[ 23]}. 此外, 储氢合金中非晶结构的形成, 不利于合金容量, 却有利于合金循环稳定性的改善, 主要是非晶相不仅具有抗粉化能力而且有很好的抗腐蚀能力^{[ 24, 25]}. 快淬后合金中形成的新相对合金的循环稳定性也有很大影响. 研究表明^{[ 26]}, LaNi₃相的晶胞体积比LaNi₅相更易膨胀, 在吸放氢过程中, LaNi₃相更容易粉化, 从而不利于循环稳定性. 快淬速度大于20 m/s复合合金的容量保持率随快淬速度的增大而逐渐减小, R30的容量保持率仅为86.4%. 结合前面XRD和TEM分析认为, 尽管随着快淬速度的增大, 快淬态合金晶粒在减小, 非晶化程度在增强, 这是有利于合金循环稳定性改善的. 但是快淬后合金中形成了较多的新相(La,Mg)Ni₃对合金循环稳定性是不利的. 一方面(La,Mg)Ni₃相易粉化, 导致合金活性物质总量减少而最终导致合金容量衰退; 另一方面合金中(La,Mg)Ni₃相含量大幅度增大的同时LaNi₅相的相对含量就会减少, 尽管(La,Mg)Ni₃相有很大的吸氢容量, 但由于缺少LaNi₅相的催化作用, 电化学反应迟钝, 可逆放氢能力下降, 发生不可逆氢化, 导致合金活性物质利用率减少而最终导致合金容量衰退.

3 结论

1) 铸态AB₅/5wt% Mg₂Ni复合合金由LaNi₅相和少量的Mg₂Ni相组成. 复合合金经快淬处理后, 快淬态复合合金由(La,Mg)Ni₃新相和LaNi₅相组成. 随着快淬速度的增加, 复合合金颗粒微观组织的晶态由粗大的晶粒逐渐转变为细小的纳米晶, 同时伴有部分非晶化倾向. 同一快淬态复合合金中LaNi₅相主要以非晶态结构存在, 而(La,Mg)Ni₃相仍以晶态组织结构存在.

2) 与AB₅合金相比, 铸态AB₅/5wt% Mg₂Ni复合合金的最大放电容量和容量保持率均有所增加, 但增加的幅度很有限. 而AB₅/5wt% Mg₂Ni复合合金经快淬处理后, 合金的最大放电容量和容量保持率均得到了明显提高. 随着快淬速度的增加, 快淬态复合合金的最大放电容量和容量保持率均呈现出先增加后减少的变化规律, 其中快淬速度为20 m/s时合金电极的最大放电容量达到344 mAh/g, 经100次充放电循环后, 其容量保持率为93.9 %.

Reference

View Option

[1]	Tliha M, Mathlouthi H, Khaldi C, et al. Electrochemical properties of the LaNi_{3. 55}Mn_{0. 4}Al_{0. 3}Co_{0. 4}Fe_{0. 35} hydrogen storage alloy. Journal of Power Sources, 2006, 160(2): 1391-1394. [Cited within: 1] [JCR: 4.675]
[2]	WEI Xue-Dong, DONG Hui, LIU Yong-Ning, et al. The effect of partial substitution of Si for Ni on the electrochemical properties of cobalt-free LaNi_{4. 2}-_xAl_{0. 35}Mn_{0. 45}Si_x (x = 0-0. 35) alloys. Journal of Alloys and Compounds, 2009, 481(1/2): 687-691. [Cited within: 1] [JCR: 2.39]
[3]	Li S L, Wang P, Chen W, et al. Hydrogen storage properties of LaNi_{3. 8}Al_{1. 0}M_{0. 2} (M = Ni, Cu, Fe, Al, Cr, Mn) alloys. Journal of Alloys and Compounds, 2009, 485(1/2): 867-871. [Cited within: 1] [JCR: 2.39]
[4]	TIAN Xiao, LIU Xiang-Dong, XU Jin, et al. Microstructures and electrochemical characteristics of Mm_{0. 3}Ml_{0. 7}Ni_{3. 55}Co_{0. 75}Mn_{0. 4}Al_{0. 3} hydrogen storage alloys prepared by mechanical alloying. International Journal of Hydrogen Energy, 2009, 34(5): 2295-2302. [Cited within: 1] [JCR: 3.548]
[5]	ZHAO Xian-Yu, DING Yi, YANG Meng, et al. Effect of surface treatment on electrochemical properties of MmNi_{3. 8}Co_{0. 75}Mn_{0. 4}Al_{0. 2} hydrogen storage alloy. International Journal of Hydrogen Energy, 2008, 33(1): 81-86. [Cited within: 1] [JCR: 3.548]
[6]	Li S L, Wang P, Chen W, et al. Effect of non-stoichiometry on hydrogen storage properties of La(Ni_{3. 8}Al_{1. 0}Mn_{0. 2})_x alloys. International Journal of Hydrogen Energy, 2010, 35(8): 3537-3545. [Cited within: 1] [JCR: 3.548]
[7]	ZHANG Wen-Cui, HAN Shu-Min, HAO Jian-Sheng, et al. Study on kinetics and electrochemical properties of low-Co AB₅-type alloys for high-power Ni/MH battery. Electrochimica Acta, 2009, 54(4): 1383-1387. [Cited within: 1] [JCR: 3.777]
[8]	WANG Yan-Zhi, ZHAO Min-Shou, LI Shu-Cun. Recent progress in study of composite hydrogen storage alloy as negative electrode material in Ni/MH battery. Rare Metal Materials and Engineering, 2008, 37(2): 195-199. [Cited within: 1] [JCR: 0.16] [CJCR: 0.827]
[9]	LIU Su-Qin, CHEN Dong-Yang, HUANG Ke-Long, et al. Preparation and electrochemical characteristics of MgNi-TiNi_{0. 56}M_{0. 44} (M=Al, Fe) alloys. Journal of Inorganic Materials, 2009, 24(2): 361-366. [Cited within: 1] [JCR: 0.531] [CJCR: 1.106]
[10]	LIU Xiang-Dong, HUANG Li-Hong, TIAN Xiao, et al. Activation characteristics and microstructure of Mg₂Ni/ Mm_{0. 3}Ml_{0. 7}Ni_{3. 55}Co_{0. 75}Mn_{0. 4}Al_{0. 3} composite hydrogen storage alloys prepared by two-step re-melting. International Journal of Hydrogen Energy, 2007, 32(18): 4939-4942. [Cited within: 2] [JCR: 3.548]
[11]	WANG Yan-Zhi, ZHAO Min-Shou. Structure and electrochemical characteristics of Ti_{0. 10}Zr_{0. 15}V_{0. 35}Cr_{0. 10}Ni_{0. 30}-LaNi₄Al_{0. 4}Mn_{0. 3}Co_{0. 3} composite hydrogen storage alloy. International Journal of Hydrogen Energy, 2010, 35(15): 8268-8274. [Cited within: 1] [JCR: 3.548]
[12]	Lü Dong-Sheng, LI Wei-Shan, TANG Ren-Heng, et al. Crystallite size and electrochemical performance of metal hydrides based on LaNi₅ prepared by twin-roll process. Journal of Inorganic Materials, 2005, 20(4): 859-863. [Cited within: 1] [JCR: 0.531] [CJCR: 1.106]
[13]	Lin H J, Ouyang L Z, Wang H, et al. Phase transition and hydrogen storage properties of melt-spun Mg₃LaNi_{0. 1} alloy. International Journal of Hydrogen Energy, 2012, 37(1): 1145-1150. [Cited within: 1] [JCR: 3.548]
[14]	TIAN Xiao, LIU Xiang-Dong, YAO Zhao-Quan, et al. Microstructures and electrochemical properties of AB₅-type rare earth hydrogen storage alloys prepared by rapid quenching. Journal of Inner Mongolia University (Natural Science Edition), 2011, 42(6): 671-676. [Cited within: 1] [CJCR: 0.1026]
[15]	TIAN Xiao, LIU Xiang-Dong, MA Fan, et al. Effects of compacttion pressure on the electrochemical properties of Mm_{0. 3}Ml_{0. 7}Ni_{3. 55}Co_{0. 75}Mn_{0. 4}Al_{0. 3} metal hydride electrodes. Journal of Alloys and Compounds, 2011, 509(5): 1734-1738. [Cited within: 1] [JCR: 2.39]
[16]	崔忠圻. 金属学与热处理. 北京: 机械工业出版社, 2004: 83-87. [Cited within: 1]
[17]	ZHANG Zhong, HAN Shu-Min, LI Yuan, et al. Electrochemical properties of Ml₁-_xMg_xNi_{3. 0}Mn_{0. 10}Co_{0. 55}Al_{0. 10} (x = 0. 05-0. 30) hydrogen storage alloys. Journal of Alloys and Compounds, 2007, 431(1/2): 208-211. [Cited within: 1] [JCR: 2.39]
[18]	PAN Hong-Ge, LIU Yong-Feng, GAO Ming-Xia, et al. A study of the structural and electrochemical properties of La_{0. 7}Mg_{0. 3}(Ni_{0. 85}Co_{0. 15})_x (x = 2. 5-5. 0) hydrogen storage alloys. Journal of the Electrochemical Society, 2003, 150(5): A565-A570. [Cited within: 1] [JCR: 2.588]
[19]	XIAO Xue-Zhang, WANG Xin-Hua, CHEN Li-Xin, et al. Microstructure and hydrogen storage properties of La_{1. 8}Ca_{0. 2}Mg₁₄Ni₃ + x% Ti composites. Rare Metal Materials and Engineering, 2007, 36(5): 790-793. [Cited within: 1] [JCR: 0.16] [CJCR: 0.827]
[20]	LI Yang, Cheng Yang-Tse. Amorphous La-Ni thin film electrodes. Journal of Alloys and Compounds, 1995, 223(1): 6-12. [Cited within: 1] [JCR: 2.39]
[21]	Züttel A, Meli F, Schlapbach L. AB₂ and AB₅ metal hydride electrodes: a phenomenological model for the cycle life. Journal of Alloys and Compounds, 1993, 200(1/2): 157-163. [Cited within: 1] [JCR: 2.39]
[22]	ZHANG Yang-Huan, LI Bao-Wei, REN Hui-Ping, et al. Cycle stabilities of the La_{0. 7}Mg_{0. 3}Ni_{2. 55}-_xCo_{0. 45}M_x (M = Fe, Mn, Al; x = 0, 0. 1) electrode alloys prepared by casting and rapid quenching. Journal of Alloys and Compounds, 2008, 458(1/2): 340-345. [Cited within: 1] [JCR: 2.39]
[23]	ZHANG Yang-Huan, WANG Guo-Qing, DONG Xiao-Ping, et al. Effect of substituting Co with Fe on the cycle stabilities of the as-cast and quenched AB₅-type hydrogen storage alloys. Journal of Power Sources, 2005, 148: 105-111. [Cited within: 1] [JCR: 4.675]
[24]	李锐. 钛钒基贮氢电极合金结构、性能及其衰退机理研究. 杭州: 浙江大学博士论文, 2007. [Cited within: 1]
[25]	ZHANG Yang-Huan, DONG Xiao-Ping, GUO Shi-Hai, et al. The cycle stabilities of the as-cast and quenched La₂Mg(Ni_{0. 85}Co_{0. 15})₉M_x (M = B, Cr, Ti; x = 0, 0. 1) hydrogen storage alloys. Journal of Alloys and Compounds, 2005, 398(1/2): 178-183. [Cited within: 1] [JCR: 2.39]
[26]	Iwakura C, Oura T, Inoue H, et al. Effects of substitution with foreign metals on the crystallographic, thermodynamic and electrochemical properties of AB₅-type hydrogen storage alloys. Electrochimica Acta, 1996, 41(1): 117-121. [Cited within: 1] [JCR: 3.777]

2006

4.675

0.0

... 就综合性能而言, AB₅ 型储氢合金仍是金属氢化物/镍(MH/Ni)电池的主要负极材料^[1] ...

2009

2.39

0.0

... 并且Co元素的使用, 使合金的成本居高不下, 越来越无法适应现代市场的要求^[2] ...

2009

2.39

0.0

... 为此, 国际上主要从两方面开展研究: 一是通过合金成分优化或合金微结构改变来改善AB₅型合金的性能^[3,4,5,6,7], 相关研究取得了很大进展, 继续这方面的研究对于储氢性能提升的力度已经很小 ...

2009

3.548

0.0

TIAN

Xiao

, LIU

Xiang-Dong

, XU

Jin

, et al. Microstructures and electrochemical characteristics of Mm_{0. 3}Ml_{0. 7}Ni_{3. 55}Co_{0. 75}Mn_{0. 4}Al_{0. 3} hydrogen storage alloys prepared by mechanical alloying. International Journal of Hydrogen Energy, 2009, 34(5): 2295-2302.

Abstract

The as-cast alloy with the composition of Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3 prepared by induction melting was milled for 6, 15, 40 and 50 h in this work. The microstructures of alloys were analyzed by XRD and DSC. Two broadening effects of XRD peak caused by crystallite and microstrain were separated by approximate function method and least square method. Crystallite sizes and microstrains of the alloys were calculated. The results show that alloys milled for 6 h or 15 h consist of nanocrystalline and polycrystalline phase. Lattice parameters (a, c) and volumes of alloy increase with the increasing milling time, whereas the ratio of c/a keep constant. Moreover, the crystallite sizes decrease and the microstrains in the alloys increase first and then decrease with the increase of milling time. The alloys milled for 40 h or 50 h transform partly into amorphous structures. The maximum discharge capacities of alloys decrease with the increase of milling time. The cycle stabilities of the milled alloys are better than those of the as-cast. And they increase with the increasing milling time.

2008

3.548

0.0

ZHAO

Xian-Yu

, DING

, YANG

Meng

, et al. Effect of surface treatment on electrochemical properties of MmNi_{3. 8}Co_{0. 75}Mn_{0. 4}Al_{0. 2} hydrogen storage alloy. International Journal of Hydrogen Energy, 2008, 33(1): 81-86.

Abstract

Surface treatment of the MmNi_3.8Co_0.75Mn_0.4Al_0.2 (Mm=Ce-rich mischmetal) hydrogen storage alloy is carried out by using the solution of HF and KF with a little addition of KBH₄. The electrochemical properties of the original and the treated hydrogen storage alloys are investigated. The discharge properties such as discharge capacity, potential plateau, and high rate dischargeability (HRD) are improved after the treatment. At a current rate of 900 mA/g, the HRD of the treated alloy still remains a high value of 80.2% while the original one cannot discharge. The result of the linear polarization measurement shows that the exchange current density increases from 80.99 to 124.98 mA/g and the polarization resistance decreases from 371.1 to after the treatment. The result of the electrochemical impedance spectroscopy (EIS) also demonstrates the same consequence. The hydrogen diffusion coefficient studied by potential-step measurement increases from 1.79×10^-9 to after the treatment.

2010

3.548

0.0

S L

, Wang

, Chen

, et al. Effect of non-stoichiometry on hydrogen storage properties of La(Ni_{3. 8}Al_{1. 0}Mn_{0. 2})_x alloys. International Journal of Hydrogen Energy, 2010, 35(8): 3537-3545.

Abstract

The La(Ni_3.8Al_1.0Mn_0.2)_x (x = 0.94, 0.96, 0.98, 1.0) hydrogen storage alloys have been investigated to examine the effect of non-stoichiometry on the crystal structure, activation performance, hydrogen absorption/desorption properties and cycle life. It was found that for the stoichiometric compound, only single phase with CaCu₅ type structure exists. However, for B-poor compounds of AB₅ alloys, there is a principal CaCu₅ type phase with a small amount of second phase and the amount of second phase increased with decreasing x when x ≥ 0.96 and reached a maximum when x = 0.96. The activation becomes harder with decreasing x until x = 0.96 and easier when x decreased to 0.94. The plateau pressure increased and the hydrogen uptake capacity decreased with decreasing x when x ≥ 0.96, and then decreased and increased, respectively, when x further decreased to 0.94. Both the change in the lattice strain which could be estimated by FWHM (full width at half maximum) and the degree of slope factor S_f in the alloys show the same trend with the change of x, exhibiting a maximum at x = 0.96. The ΔH decreased with decreasing x when x ≥ 0.96 and then increased when x = 0.94 and it was found that the larger the cell volume, the larger the absolute value of the enthalpy. The pulverization resistance of the alloys was greatly improved by the non-stoichiometric. The kinetics of the alloys was very fast and almost not influenced by the change of non-stoichiometric x. After 300 absorption/desorption cycles, the hydrogen uptake capacity of the stoichiometric and non-stoichiometric alloys almost kept the same, but the particle size decreased greatly.

2009

3.777

0.0

ZHANG

Wen-Cui

, HAN

Shu-Min

, HAO

Jian-Sheng

, et al. Study on kinetics and electrochemical properties of low-Co AB₅-type alloys for high-power Ni/MH battery. Electrochimica Acta, 2009, 54(4): 1383-1387.

Abstract

The structure and electrochemical kinetics properties of La_0.90−xCe_xPr_0.05Nd_0.05Ni_3.90Co_0.40Mn_0.40Al_0.30 (x = 0.10, 0.20, 0.30, 0.40, 0.50) hydrogen storage alloys have been investigated. XRD shows that the alloys consist of LaNi₅ phase with hexagonal CaCu₅ structure. With increase in Ce content, the parameter a and cell volume decrease remarkably, but the parameter c increases slightly. The limiting current density I_L and the hydrogen diffusion coefficient D increase, and the exchange current density I₀ increases firstly from 201.4 mA/g (x = 0.10) to 277.9 mA/g (x = 0.30) and then decreases to 208.5 mA/g (x = 0.50). Meanwhile, high rate dischargeability (HRD) at 1440 mA/g increases from 44.1% (x = 0.10) to 59.9% (x = 0.30), and then decreases to 44.2% (x = 0.50). As the amount of Ce increases, the plateau pressure of P–C isotherms increases gradually, the capacity retention of the alloys increases firstly and then decreases, the alloy with x = 0.30 has the higher capacity retention and cycling stability, but the maximum discharge capacity of alloys decreases. Ce is a vital element in favor of kinetics properties of rare earth-based AB₅-type alloys, and the substitution of La with Ce in suitable amount could improve the HRD by increasing kinetics.

2008

0.16

0.827

... 近年来, 国内外研究者在复合合金的类型、组元含量、制备工艺等方面开展了一些相关研究^[8,9,10,11] ...

2009

0.531

1.106

LIU

Su-Qin

, CHEN

Dong-Yang

, HUANG

Ke-Long

, et al. Preparation and electrochemical characteristics of MgNi-TiNi_{0. 56}M_{0. 44} (M=Al, Fe) alloys. Journal of Inorganic Materials, 2009, 24(2): 361-366.

MgNi and MgNi-TiNi_0.56M_0.44（M=Al,Fe）alloys were successfully synthesized by mechanical alloying (MA) approach. The structure and the electrochemical characteristics of these Mg-based electrodes were studied. The results of X-ray diffraction and scanning electron microscope show that the alloys have amorphous structures. The chargedischarge cycle tests indicate that the cycle performance of these alloys are better than those of MgNi alloys, although the first discharge capacities are lower than that of the MgNi alloys. Among these alloys, the discharge capacity of MgNi-TiNi_0.56Al_0.44 is the highest, up to 380.64mAh/g，and the capacity maintaining rate is 48.97％ after 50 cycles. Potentiodynamic polarization curves prove that anti-corrosion performance of the electrodes become better. Cyclic voltammetry (CV) and electrochemical impedance spectroscope (EIS) tests show that the introduction of the TiNi_0.56M_0.44（M=Al,Fe）alloys decrease the charge-transfer reaction resistance and the H atom diffusion impedance, and improve the electrode catalytic activity significantly.

College of Chemistry ＆ Chemical Engineering, Central South University, Changsha 410083, China

用机械合金化法制备出MgNi及MgNi-TiNi_0.56M_0.44（M=Al、Fe）复合合金,并研究该系列合金的相结构和电化学性能. XRD结果表明所合成的几种合金均为非晶态；充放电结果表明：MgNi-TiNi_0.56M_0.44（M=Al、Fe）复合合金的初始容量比纯MgNi合金低，但循环寿命有较大的改善，其中MgNi-TiNi_0.56Al_0.44合金放电容量最大，达380.64mAh/g,经50次循环后容量保持率是48.97％；动电位扫描结果表明复合后合金电极的抗腐蚀能力增强；循环伏安法和电化学阻抗谱法研究结果表明：复合后降低了电极表面的电子转移电阻和H原子的扩散阻抗，增强了电极表面的电化学催化性能.

... 近年来, 国内外研究者在复合合金的类型、组元含量、制备工艺等方面开展了一些相关研究^[8,9,10,11] ...

2007

3.548

0.0

LIU

Xiang-Dong

, HUANG

Li-Hong

, TIAN

Xiao

, et al. Activation characteristics and microstructure of Mg₂Ni/ Mm_{0. 3}Ml_{0. 7}Ni_{3. 55}Co_{0. 75}Mn_{0. 4}Al_{0. 3} composite hydrogen storage alloys prepared by two-step re-melting. International Journal of Hydrogen Energy, 2007, 32(18): 4939-4942.

Abstract

In the present work, novel composites (x=0,5,10,30) for hydrogen storage were prepared by two-step re-melting and their activation characteristic and microstructure were investigated. The influence of Mg₂Ni content on the activation characteristics was analyzed by electrochemical method. With the increasing content of Mg₂Ni, activation characteristics and maximum discharge capacities of composites increase first and then decrease. The composite with 5% Mg₂Ni has the least cycle number for activation and the highest discharge capacity. It is activated after only 6 cycles (C_n=6) at room temperature and its maximum discharge capacity (C_max) reaches 274.4 mAh/g. However, the composite contained 30 wt% Mg₂Ni is difficult to be activated at room temperature. It is also found that it is easier to be activated for the composites at and than that at and , but their discharge capacity decay slightly at the condition of and . The XRD and SEM analysis show that, with the increasing Mg₂Ni content, the microstructure of the composites varies gradually from lamellar (x=5), acicular (x=10) to massive (x=30), and the activity of the composite declines as a result of the grain size of phase Mg₂Ni grows up.

... 近年来, 国内外研究者在复合合金的类型、组元含量、制备工艺等方面开展了一些相关研究^[8,9,10,11] ...

... 前期, Liu等^[10]采用二步熔炼法将难活化、高容量、低廉价格的Mg₂Ni储氢合金与易活化、低容量、高成本的AB₅型储氢合金进行复合 ...

2010

3.548

0.0

WANG

Yan-Zhi

, ZHAO

Min-Shou

. Structure and electrochemical characteristics of Ti_{0. 10}Zr_{0. 15}V_{0. 35}Cr_{0. 10}Ni_{0. 30}-LaNi₄Al_{0. 4}Mn_{0. 3}Co_{0. 3} composite hydrogen storage alloy. International Journal of Hydrogen Energy, 2010, 35(15): 8268-8274.

Abstract

Structure and electrochemical characteristics of Ti_0.10Zr_0.15V_0.35Cr_0.10Ni_0.30 (matrix alloy) — 1 mass% LaNi₄Al_0.4Mn_0.3Co_0.3 composite hydrogen storage alloy have been investigated systematically. The main phase of composite alloy is composed of V-based solid solution phase with a BCC structure and C14 Laves phase with hexagonal structure, while secondary phase which has a composition close to Zr (Ti, V, Ni, Cr, Al, Co, La)_1.8 also exists in the composite alloy. The real maximum discharge capacity of the composite alloy electrode is 354.9 mAh g⁻¹, and distinct synergetic effect appears during composite process. Comparing with the matrix alloy, the thermodynamic performances, electrochemical characteristics, dynamic performances for the composite alloy electrode have been improved. The secondary phase is probably responsible for the improvement of electrochemical characteristics of the matrix alloy.

... 近年来, 国内外研究者在复合合金的类型、组元含量、制备工艺等方面开展了一些相关研究^[8,9,10,11] ...

2005

0.531

1.106

Lü

Dong-Sheng

, LI

Wei-Shan

, TANG

Ren-Heng

, et al. Crystallite size and electrochemical performance of metal hydrides based on LaNi₅ prepared by twin-roll process. Journal of Inorganic Materials, 2005, 20(4): 859-863.

AB_₅-type hydrogen storage alloy La_0.65Ce_0.28Pr_0.02Nd_0.05Ni_3.8Co_0.7Mn_0.3Al_0.2 was prepared by twin-roll process, and the microstructure, capacity and cyclic
stability of the alloy were characterized by SEM, XRD and constant current charge and discharge. The alloy has a uniform nano-scale crystallite size
of about 40nm. Its discharge capacity is 336mAh/g at 0.2C rate (64mA/g), and 312mAh/g at 2C rate (640mA/g) and retains 80% of the initial capacity after
400 cycles. The influence of La content on electrochemical capacity and cyclic stability of the alloy was also studied. It is found that discharge capacity
of the alloy increases with the increase of La content when La less than 60wt% and keeps unchanging from 60% to 80%. However, cyclic stability of
the alloy decreases with the increase of La content.

1. Department of Chemistry; South China Normal University; Guangzhou 510631; China; 2. Guangzhou Institute for Nonferrous Metal Research; Guangzhou 510651; China

使用双辊淬冷技术制备了LaNi₅基AB₅型贮氢合金,用扫描电镜和X射线衍射确定合金的晶粒尺寸,用恒电流充放电方法确定合金的电化学容量及其循环稳定性.结果表明, 制备的合金具有均匀的纳米晶结构;在64mA/g(约0.2C)的电流密度下,合金放电容量高达336mAh/g,而在640mA/g(约2C)的电流密度下,合金放电容量仍达312mAh/g,经400次循环后容量保持约80%.另外,还研究了La含量对合金容量和循环稳定性的影响,合金容量在La 含量<60%范围内,随La含量增加而增加,La含量从60%增至80%,合金容量保持不变, 但是合金循环稳定性随La含量增加而减少.

... 真空快淬工艺是一种通过控制冷却速度的快速凝固非平衡合金制备方法, 可以快速地改变合金的微结构, 使合金获得纳米晶、非晶和微晶等亚稳态结构^[12,13] ...

2012

3.548

0.0

2011

0.0

0.1026

2011

2.39

0.0

... 合金电极的活化性能和循环稳定性充放电制度参见文献^[15] ...

2004

0.0

... T可以表示^[16]为: ...

2007

2.39

0.0

... 研究表明^[17], LaNi₃相的储氢量远高于LaNi₅相 ...

2003

2.588

0.0

... 晶态的LaNi₅相在合金中具有双重作用, 一方面起着吸氢作用, 另一方面由于含有高Ni含量对自身以及其它吸氢相(例如(La,Mg)Ni₃相)的电化学反应起着催化作用^[18] ...

2007

0.16

0.827

... (3) 合金晶粒细化也有利于储氢容量的提高^[19] ...

1995

2.39

0.0

... 容量减小的主要原因是合金中形成的非晶相随快淬速度的增大而逐渐增多, 因为非晶相的储氢容量只有其晶态的一半左右^[20] ...

1993

2.39

0.0

... 研究表明^[21,22], 在储氢合金充放电循环过程中, 导致合金循环稳定性下降的因素有3种: 一是合金的粉化 ...

2008

2.39

0.0

... 研究表明^[21,22], 在储氢合金充放电循环过程中, 导致合金循环稳定性下降的因素有3种: 一是合金的粉化 ...

2005

4.675

0.0

... 本研究中容量保持率随快淬速度的增大得以改善主要归因于快淬导致复合合金中合金晶粒尺寸减小, 合金晶粒的强度和韧性增强, 合金越不易粉化^[23] ...

2007

0.0

... 此外, 储氢合金中非晶结构的形成, 不利于合金容量, 却有利于合金循环稳定性的改善, 主要是非晶相不仅具有抗粉化能力而且有很好的抗腐蚀能力^[24,25] ...

2005

2.39

0.0

1996

3.777

0.0

... 研究表明^[26], LaNi₃相的晶胞体积比LaNi₅相更易膨胀, 在吸放氢过程中, LaNi₃相更容易粉化, 从而不利于循环稳定性 ...