Improved hydrogen storage kinetics of the Li-Mg-N-H system by addition of Mg(BH4)2
Improved hydrogen storage kinetics of the Li-Mg-N-H system by addition of Mg(BH4)2
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通过添加 Mg(BH4)2 改善 Li-Mg-N-H 系统的储氢动力学
DOI：
10.1039/c2dt32266h
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发表时间：
2013-01-01
影响因子：
4
通讯作者：
Gao, Mingxia
中科院分区：
文献类型：
--
作者：
Pan, Hongge;Shi, Songbo;Gao, Mingxia
采用球磨法制备了Mg(BH4)(2)添加Mg(NH2)(2)-2LiH体系。系统研究了Mg(NH2)(2)-2LiH-xMg(BH4)(2) （x = 0、0.1、0.2、0.3）样品的储氢性能及Mg(BH4)(2)的储氢作用。结果表明，加入Mg(BH4)(2)的Mg(NH2)(2)-2LiH试样解吸氢的起始温度和峰值温度向低温转移；其中，Mg(NH2)(2)-2LiH-0.1Mg(BH4)(2)样品在120 ~ 150℃的温度范围内可可逆吸收接近4.5 wt%的氢，优于原始样品。在球磨过程中，Mg(BH4)(2)和LiH容易发生反应生成LiBH4和MgH2，随后，新生成的MgH2与Mg(NH2)(2)反应生成MgNH。加热后，LiBH4的存在不仅降低了Mg(NH2)(2)的再结晶温度，而且与LiNH2反应生成Li-4(BH4)(NH2)(3)中间体，削弱了N-H键，提高了离子电导率。同时，由于结构相似，MgNH可能作为Li2MgN2H2脱氢产物的成核中心。因此，原位形成的LiBH4和MgNH协同作用，提高了Mg(NH2)(2)-2LiH体系的储氢性能。
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 similar to 4.5 wt% of hydrogen in the temperature range of 120-150 degrees 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 Li-4(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.