Crystallographic and electrochemical characteristics of La0.7Mg0.3Ni3 − x(Al0.5Mo0.5)x (x = 0–0.4) hydrogen storage alloys
Crystallographic and electrochemical characteristics of La0.7Mg0.3Ni3 − x(Al0.5Mo0.5)x (x = 0–0.4) hydrogen storage alloys
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DOI：
10.1016/j.electacta.2004.12.020
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发表时间：
2005-05
影响因子：
6.6
通讯作者：
X. Zhang;D. Sun;W. Yin;Y. Chai;Min-shou Zhao
中科院分区：
文献类型：
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作者：
X. Zhang;D. Sun;W. Yin;Y. Chai;Min-shou Zhao
系统研究了Al和Mo部分替代Ni对La0.7Mg0.3Ni3−x（Al0.5Mo0.5）x（x=0-0.4）贮氢合金结构和电化学性能的影响。X射线粉末衍射（XRD）和Rietveld分析结果表明，所有合金均由La（La，Mg）2Ni 9和LaNi 5相组成。同时，La（La，Mg）2Ni 9相和LaNi 5相的晶格常数和晶胞体积均随Al和Mo含量的增加而增大。压力组成等温曲线表明，随着x的增加，储氢量先增加后减小。电化学测试表明，合金电极的最大放电容量从343.3（x=0）增加到377.6mAh/g（x=0.3），然后下降到350.4mAh/g（x=0.4）。合金电极的高倍率放电性能和交换电流密度随合金中x的增加先减小后增大。氢的扩散系数随Al和Mo含量的增加而增加，从而提高了合金电极的低温放电性能（LTD）。
The effect of partial substitution of Al and Mo for Ni on the structure and electrochemical properties of the La0.7Mg0.3Ni3−x(Al0.5Mo0.5)x(x=0–0.4) hydrogen storage alloys have been investigated systematically. The result of X-ray powder diffraction (XRD) and Rietveld analysis show that all the alloys consist of the La(La, Mg)2Ni9phase and the LaNi5phase. Meanwhile, the lattice parameter and the cell volume of both the La(La, Mg)2Ni9phase and the LaNi5phase increase with increasing Al and Mo contents in the alloys. The pressure composition isotherms curves indicate that the hydrogen storage capacity first increases and then decreases with increasing x. The electrochemical measurements show that the maximum discharge capacity of the alloy electrodes first increases from 343.3 (x=0) to 377.6mAh/g (x=0.3) and then decreases to 350.4mAh/g (x=0.4). Moreover, the high rate dischargeability (HRD) and the exchange current density of the alloy electrodes decrease first and then increases with the increase of x in the alloys. The hydrogen diffusion coefficient increases with increasing Al and Mo content and thus increases the low temperature dischargeability (LTD) of the alloy electrodes.