Structural and hydrogenation study on the ball milled TiH2–Mg–Ni
Structural and hydrogenation study on the ball milled TiH2–Mg–Ni
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DOI：
10.1016/j.ijhydene.2015.01.118
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发表时间：
2015-03
影响因子：
7.2
通讯作者：
Xianda Li;O. Elkedim;F. Cuevas;R. Chassagnon
中科院分区：
文献类型：
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作者：
Xianda Li;O. Elkedim;F. Cuevas;R. Chassagnon
为了进一步了解Ti-Ni-Mg合金及其加氢行为，将摩尔比为3：1：2的TiH 2、Mg和Ni粉末按化学计量比（TiH 2）1.5Mg0.5Ni分别机械球磨10 h、20 h、30 h和40 h。分析了球磨样品的微观结构，并研究了其作为MH-Ni电池负极材料的加氢性能。随球磨时间的变化揭示了Ti-Mg-H FCC相的快速形成。通过比较不同球磨时间下的相组成，论证了Ti、Mg和Ni之间的合金化优先性。通过固气反应和恒电流电化学循环测试表明，随着球磨时间的延长，样品的总容量逐渐增加，除了球磨10 h的样品几乎不产生可逆的储氢容量外，所有样品在前几次循环中容量下降后都表现出良好的循环稳定性。球磨40 h的样品放电容量最大，达到100 mAh/g。压力-组成-等温线（PCI）和恒电流间歇滴定法（GITT）曲线表明，所有样品均以固溶体形式吸收氢。测得的容量的结论是由Ti-Mg-H相和TiNi相，而只有后者可以提供可逆容量。
With the aim of further understanding for Ti–Ni–Mg alloys and their hydrogenation behavior, powders of TiH2, Mg and Ni with the molar ratio of 3:1:2 have been mechanically milled for 10 h, 20 h, 30 h, 40 h according to the stoichiometry (TiH2)1.5Mg0.5Ni. Microstructures of the milled sample were analyzed and their hydrogenation properties as negative electrodes for Ni-MH batteries were studied. Phase change with milling time revealed the fast formation of the Ti–Mg–H FCC phase. The alloying priority among Ti, Mg and Ni was demonstrated by comparing phase compositions in different milling time. Hydrogen capacities evaluated by both solid–gas reaction and electrochemical cycling under galvanostatic conditions show that overall capacities increase with milling time. Except for the sample milled 10 h, which hardly delivers any reversible hydrogen capacity, all samples exhibit excellent cycling stability after capacity drop in the first few cycles. The best discharge capacity 100 mAh/g is observed for the sample milled 40 h. The PCI (Pressure-Composition-Isotherms) and GITT (Galvanostatic Intermittent Titration Technique) curves indicate that all samples absorb hydrogen in solid solution. The measured capacities are concluded to be contributed by the Ti–Mg–H phase and the TiNi phase, while only the latter can provide reversible capacity.