Superior low-temperature hydrogen release from the ball-milled NH₃BH₃-LiNH₂-LiBH₄ composite

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• 作者：Junhong Luo ; Xiangdong Kang ; Ping Wang ; ^{pingwang@imr.ac.cn}
• 关键词：Hydrogen storage ; Dehydrogenation ; Ammonia borane ; Lithium amide ; Lithium borohydride
• 刊名：International Journal of Hydrogen Energy
• 出版年：2013
• 出版时间：15 April, 2013
• 年：2013
• 卷：38
• 期：11
• 页码：4648-4653
• 全文大小：630 K

文摘

In the present study, we employed a multi-component combination strategy to constitute an AB/LiNH₂/LiBH₄ composite system. Our study found that mechanically milling the AB/LiNH₂/LiBH₄ mixture in a 1:1:1 molar ratio resulted in the formation of LiNH₂BH₃ (LiAB) and new crystalline phase(s). A spectral study of the post-milled and the relevant samples suggests that the new phase(s) is likely ammoniate(s) with a formula of Li_2?x(NH₃)(NH₂BH₃)_1?x(BH₄) (0?<?x?<?1). The decomposition behaviors of the Li_2?x(NH₃)(NH₂BH₃)_1?x(BH₄)/xLiAB composite were examined using thermal analysis and volumetric method in a wide temperature range. It was found that the composite exhibited advantageous dehydrogenation properties over LiAB and LiAB¡¤NH₃ at moderate temperatures. For example, it can release ¡«7.1?wt % H₂ of purity at temperature as low as 60?¡ãC, with both the dehydrogenation rate and extent far exceeding that of LiAB and LiAB¡¤NH₃. A selectively deuterated composite sample has been prepared and examined to gain insight into the dehydrogenation mechanism of the Li_2?x(NH₃)(NH₂BH₃)_1?x(BH₄)/xLiAB composite. It was found that the LiBH₄ component does not participate in the dehydrogenation reaction at moderate temperatures, but plays a key role in strengthening the coordination of NH₃. This is believed to be a major mechanistic reason for the favorable dehydrogenation property of the composite at moderate temperatures.