Enhanced reversible hydrogen desorption properties and mechanism of Mg(BH4)(2)-AlH3-LiH composite
Enhanced reversible hydrogen desorption properties and mechanism of Mg(BH4)(2)-AlH3-LiH composite
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Mg(BH4)(2)-AlH3-LiH复合材料增强可逆氢解吸性能及机理
DOI：
10.1016/j.jallcom.2018.05.267
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发表时间：
2018
影响因子：
6.2
通讯作者：
Chen Lixin
中科院分区：
文献类型：
--
作者：
Zheng Jiaguang;Xiao Xuezhang;He Yan;Chen Man;Liu Meijia;Li Shouquan;Chen Lixin
采用机械球磨的方法合成了新型三元化合物Mg(BH4)2-AlH3-xLiH(x= 0，0.5，1)，并对其良好的脱氢性能和机理进行了实验研究。结果表明，在球磨过程中，少量的Mg(BH4)2会与LiH反应生成LiBH4，而球磨后大部分的Mg(BH4)2保持稳定。在Mg(BH4)2-AlH3-xLiH复合材料中可以检测到两个主要的脱氢步骤，分别属于AlH3和Mg(BH4)2的分解。值得注意的是，Mg(BH4)2-AlH3-xLiH复合材料的起始放氢温度可降低到125.9 °C，总放氢量为10.3 wt%。值得强调的是，与Mg(BH4)2-AlH3复合材料相比，可逆脱氢能力明显提高，达到3.8wt%( )。这种可逆容量可以保持3次循环，没有明显的退化。通过对脱氢/复氢复合材料的微观结构分析，确定了[BH4]-In Mg(BH4)2-AlH3-0.5LiH复合材料的再生过程，揭示了LiH在循环放氢和吸氢过程中的作用。MgAlB4和LiH之间二次加氢生成的LiBH4和MgH有助于可逆储氢性能的稳定。
The Mg(BH4)2-AlH3-xLiH (x= 0, 0.5, 1) novel ternary composites have been synthesized through mechanical ball milling, their favorable dehydrogenation properties and mechanism have been experimentally investigated. It can be found that during ball milling, a slight amount of Mg(BH4)2would react with LiH and transform into LiBH4, while most Mg(BH4)2remained stable after ball milling. Two major dehydrogenation steps can be detected in the Mg(BH4)2-AlH3-xLiH composite, which belong to the decomposition of AlH3and Mg(BH4)2, respectively. Remarkably, the onset hydrogen desorption temperature of Mg(BH4)2-AlH3-xLiH composite can be reduced to 125.9 °C, with a total hydrogen desorption capacity of 10.3 wt%. It is worth emphasizing that the reversible dehydrogenation capacity is obviously improved to 3.8 wt%, compared to the Mg(BH4)2-AlH3composite. This reversible capacity can be held for 3 cycles without obvious degeneration. Microstructural analysis on de/rehydrogenated composite has identified the regeneration of [BH4]-in Mg(BH4)2-AlH3-0.5LiH composite and revealed the role of LiH in the cycling hydrogen desorption and absorption processes. The formation of LiBH4and MgH2resulted from the rehydrogenation between MgAlB4and LiH could be helpful for the stability of reversible hydrogen storage performance.