Reversible De/hydriding Reactions between Two New Mg鈥揑n鈥揘i Compounds with Improved Thermodynamics and Kinetics

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• 作者：Yanshan Lu ; Hui Wang ; Jiangwen Liu ; Liuzhang Ouyang ; Liangkui Zhu ; Daliang Zhang ; Min Zhu
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：December 3, 2015
• 年：2015
• 卷：119
• 期：48
• 页码：26858-26865
• 全文大小：637K
• ISSN：1932-7455

文摘

Magnesium-based alloys show great potential for hydrogen storage because of their high capacity, excellent reversibility, and low cost. However, the sluggish hydrogen sorption kinetics and overhigh dehydrogenation temperature hinder their practical application. In this paper, we present the reversible de/hydriding reaction mechanism of two new Mg鈥揑n鈥揘i ternary intermetallic compounds, which shows improved thermodynamics and kinetics in comparison with pure Mg. These two new phases correspond to Mg₂InNi and Mg₁₄In₃Ni₃ stoichiometries, both with orthorhombic structure, as determined by combinational X-ray diffraction and electron diffraction tomography analysis. In the hydriding process, the Mg₁₄In₃Ni₃ alloy decomposes into a mixture of MgH₂ and Mg₂InNi, which is fully reversible in the dehydrogenation with hydrogen storage capacity of 1.8 wt %. For the dehydriding of MgH₂ and Mg₂InNi, a decrease of the reaction enthalpy (70.1 kJ mol^鈥? H₂) is obtained compared with pure MgH₂ (72.2 kJ mol^鈥? H₂), and the dehydrogenation activation energy is decreased to 78.5 kJ mol^鈥? from 鈭?60 kJ mol^鈥? for pure MgH₂. Comparatively, the alloy Mg₉₀In₅Ni₅ containing the Mg₁₄In₃Ni₃ phase has higher reversible hydrogen storage capacity of 3.3 wt %, and the minimum dehydrogenation temperature is reduced to 220 掳C. This work demonstrates the potential of exploring new Mg-based intermetallic compounds for hydrogen storage applications.