Nd替代La对La-Mg-Ni系A<sub>2</sub>B<sub>7</sub>型贮氢电极合金性能的影响-有色金属在线

简介概要

Nd替代La对La-Mg-Ni系A₂B₇型贮氢电极合金性能的影响

来源期刊：中国有色金属学报2007年第1期

论文作者：周增林宋月清崔舜林晨光曲选辉

文章页码：45 - 45

关键词：钕；A₂B₇型；贮氢电极合金；相结构；p—c—t曲线；电化学性能

Key words：neodymium; A₂B₇-type; hydrogen storage electrode alloys; phase structure; p—c—t curves; electrochemical properties

摘要：

用冷坩锅磁悬浮熔炼方法制备了La_0.7_－_xNd_xMg_0.3(NiCoAl)_3.5(x=0, 0.1, 0.3, 0.5, 0.7)贮氢电极合金，采用X射线衍射Rietveld法、三电极体系及扫描电镜研究合金的相结构和电化学性能以及电极的表面状态。Rietveld法分析表明：合金为多相结构，主相均为Ce₂Ni₇型六方相，还包括CaCu₅型六方相、PuNi₃型菱方相、MgCu₂型立方相及CrB型正交相；且随着Nd含量x的增加，主相含量增加，相应CaCu₅型和MgCu₂型相含量降低，PuNi₃型相含量则在一定范围内波动；且各组成相单胞体积均呈线性降低趋势。p—c—t曲线显示，合金放氢平台区域变窄，平台压力升高，平台先稍有倾斜后逐渐平坦。电化学性能测试显示，最大放电容量基本呈线性递减；活化性能优异；高倍率放电性能先提高后稍有降低；循环稳定性得到改善。

Abstract: The La_0.7_－_xNd_xMg_0.3(NiCoAl)_3.5 (x=0, 0.1, 0.3, 0.5, 0.7) hydrogen storage electrode alloys were prepared by cold crucible melting under argon gas atmosphere. The phase structure and electrochemical properties of these alloys and the surface of corresponding electrodes were investigated by means of XRD Rietveld method and tri-electrode test system and SEM. Rietveld analyses show that all these alloys consist of hexagonal Ce2Ni7-type main-phase, hexagonal CaCu₅-type phase, rhombohedral PuNi3-type phase, cubic MgCu₂-type phase and orthorhombic CrB-type phase. The main-phase content increases, and accordingly the CaCu₅-type and MgCu₂-type phase content decreases, and the PuNi₃-type phase content is almost invariable. Furthermore, the cell volume of these phases decreases linearly. p—c—t isotherms show that hydrogen-desorption plateau region narrows with increasing x, and the plateau pressure increases and the plateau becomes firstly steeper then flatter. The electrochemical results show that maximum discharge capacity decreases linearly. The activation property and high-rate dischargeability are favorable. Cyclic stability is improved markedly.

基金信息：北京科技大学新金属材料国家重点实验室资助项目

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