A Study of the Structural and Electrochemical Properties of La0.7Mg0.3 ( Ni0.85Co0.15 ) x ( x = 2.5 5.0 ) Hydrogen Storage Alloys
A Study of the Structural and Electrochemical Properties of La0.7Mg0.3 ( Ni0.85Co0.15 ) x ( x = 2.5 5.0 ) Hydrogen Storage Alloys
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DOI：
10.1149/1.1562593
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发表时间：
2003-05
影响因子：
3.9
通讯作者：
H. Pan;Yongfeng Liu;M. Gao;Y. Lei;Qidong Wang
中科院分区：
文献类型：
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作者：
H. Pan;Yongfeng Liu;M. Gao;Y. Lei;Qidong Wang
本文系统地研究了La_(0.7)Mg_(0.3)(Ni_(0.85)Co_(0.15))x(x=2.5，3.0，3.5，4.0，4.5，5.0)储氢合金电极的结构和电化学性能。X射线衍射Rietveld分析表明，这些合金均由具有PuNi3型三方结构的(La，Mg)Ni3相和具有CaCu5型六方结构的LaNi5相组成。(La，Mg)Ni3相丰度随着x的增加先增加到一个较高的百分比(∼75%)，然后降低，而LaNi5相丰度则先保持较低的丰度，几乎不变，然后随着x的增加而增加到较高的百分比(∼70%)。电化学研究表明，合金电极的最大放电容量、高倍率放电能力、交换电流密度和极限电流密度都随着x的增加而增加，当x从3.5增加到4.5时，合金电极的最大放电容量、高倍率放电容量、交换电流密度和极限电流密度都随着x的增加而减小。
In this paper, the structural and electrochemical properties of La 0.7 Mg 0.3 (Ni 0.85 Co0.15) x (x = 2.5,3.0,3.5,4.0,4.5,5.0) hydrogen storage alloy electrodes were studied systematically. X-ray diffraction Rietveld analyses show that all these alloys consist of a (La, Mg)Ni 3 phase with the PuNi 3 -type rhombohedral structure and a LaNi 5 phase with the CaCu 5 -type hexagonal structure. The (La, Mg)Ni 3 phase abundance first increases to a high percentage (∼75%) and then decreases with increasing x. In contrast, the LaNi 5 -phase abundance first remains low and almost unchanged and then increases to a high percentage (∼70%) with increasing x. The pressure-composition isotherms shows that for each isotherm the plateau region widens and the plateau pressure is maintained almost unchanged when x increases from 2.5 to 3.5. However, as x increases further, the plateau region is shortened and becomes flatter, and the plateau pressure increases with x. Electrochemical studies indicate that all important electrochemical properties, including the maximum discharge capacity, the high rate dischargeability, the exchange current density, and the limiting current density of the alloy electrodes increase as x increases from 2.5 to 3.5 and then decrease when x increases further from 3.5 to 4.5.