State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Dalton Trans. 2013 Mar 21;42(11):3802-11. doi: 10.1039/c2dt32266h. Epub 2012 Nov 23.
A Mg(BH(4))(2)-added Mg(NH(2))(2)-2LiH system was prepared by ball milling the corresponding chemicals. The hydrogen storage properties of the Mg(NH(2))(2)-2LiH-xMg(BH(4))(2) (x = 0, 0.1, 0.2, 0.3) samples and the role played by Mg(BH(4))(2) were systematically investigated. The results show that the onset and peak temperatures for hydrogen desorption from the Mg(BH(4))(2)-added Mg(NH(2))(2)-2LiH sample shifted to lower temperatures. In particular, the Mg(NH(2))(2)-2LiH-0.1Mg(BH(4))(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(BH(4))(2) and LiH readily occurred to form LiBH(4) and MgH(2) and subsequently, the newly formed MgH(2) reacted with Mg(NH(2))(2) to generate MgNH. Upon heating, the presence of LiBH(4) not only decreased the recrystallization temperature of Mg(NH(2))(2) but also reacted with LiNH(2) to form the Li(4)(BH(4))(NH(2))(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 Li(2)MgN(2)H(2) due to the structural similarity. Thus, the in situ formed LiBH(4) and MgNH provide a synergetic effect to improve the hydrogen storage performances of the Mg(NH(2))(2)-2LiH system.
通过将相应的化学品球磨，制备了一个添加了 Mg(BH(4))(2)的 Mg(NH(2))(2)-2LiH 体系。系统研究了 Mg(NH(2))(2)-2LiH-xMg(BH(4))(2)（x=0,0.1,0.2,0.3）样品的储氢性能以及 Mg(BH(4))(2)的作用。结果表明，从添加 Mg(BH(4))(2)的 Mg(NH(2))(2)-2LiH 样品中脱氢气的起始和峰值温度向低温移动。特别是，Mg(NH(2))(2)-2LiH-0.1Mg(BH(4))(2)样品在 120-150°C 的温度范围内可可逆地吸收约 4.5wt%的氢气，优于原始样品。在球磨过程中，Mg(BH(4))(2)和 LiH 之间容易发生复分解反应，形成 LiBH(4)和 MgH(2)，随后新形成的 MgH(2)与 Mg(NH(2))(2)反应生成 MgNH。加热时，LiBH(4)的存在不仅降低了 Mg(NH(2))(2)的再结晶温度，而且与 LiNH(2)反应形成 Li(4)(BH(4))(NH(2))(3)中间产物，削弱了 N-H 键并增强了离子导电性。同时，MgNH 可能由于结构相似而作为 Li(2)MgN(2)H(2)脱氢产物的成核中心。因此，原位形成的 LiBH(4)和 MgNH 为提高 Mg(NH(2))(2)-2LiH 体系的储氢性能提供了协同效应。
