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Issue 11, 2013
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Improved hydrogen storage kinetics of the Li–Mg–N–H system by addition of Mg(BH4)2

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Abstract

A Mg(BH4)2-added Mg(NH2)2–2LiH system was prepared by ball milling the corresponding chemicals. The hydrogen storage properties of the Mg(NH2)2–2LiH–xMg(BH4)2 (x = 0, 0.1, 0.2, 0.3) samples and the role played by Mg(BH4)2 were systematically investigated. The results show that the onset and peak temperatures for hydrogen desorption from the Mg(BH4)2-added Mg(NH2)2–2LiH sample shifted to lower temperatures. In particular, the Mg(NH2)2–2LiH–0.1Mg(BH4)2 sample could reversibly absorb ∼4.5 wt% of hydrogen in the temperature range of 120–150 °C, which is superior to the pristine sample. During ball milling, a metathesis reaction between Mg(BH4)2 and LiH readily occurred to form LiBH4 and MgH2 and subsequently, the newly formed MgH2 reacted with Mg(NH2)2 to generate MgNH. Upon heating, the presence of LiBH4 not only decreased the recrystallization temperature of Mg(NH2)2 but also reacted with LiNH2 to form the Li4(BH4)(NH2)3 intermediate, which weakens the N–H bonding and enhances the ion conductivity. Meanwhile, MgNH may act as the nucleation center for the dehydrogenation product of Li2MgN2H2 due to the structural similarity. Thus, the in situ formed LiBH4 and MgNH provide a synergetic effect to improve the hydrogen storage performances of the Mg(NH2)2–2LiH system.

Graphical abstract: Improved hydrogen storage kinetics of the Li–Mg–N–H system by addition of Mg(BH4)2

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Publication details

The article was received on 27 Sep 2012, accepted on 08 Nov 2012 and first published on 23 Nov 2012


Article type: Paper
DOI: 10.1039/C2DT32266H
Dalton Trans., 2013,42, 3802-3811

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    Improved hydrogen storage kinetics of the Li–Mg–N–H system by addition of Mg(BH4)2

    H. Pan, S. Shi, Y. Liu, B. Li, Y. Yang and M. Gao, Dalton Trans., 2013, 42, 3802
    DOI: 10.1039/C2DT32266H

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