Significant effects of graphite fragments on hydrogen storage performances of LiBH₄: A first-principles approach

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• 作者：Yonghong Zhang ; Hui Ding ; Chuan Liu ; Shengli Zhang ; Shiping Huang
• 关键词：LiBH4 ; Graphite fragments ; Density-functional theory ; Hydrogen diffusion ; Hydrogen storage
• 刊名：International Journal of Hydrogen Energy
• 出版年：2013
• 出版时间：17 October, 2013
• 年：2013
• 卷：38
• 期：31
• 页码：13717-13727
• 全文大小：2681 K

文摘

The graphite fragments are used to establish the calculated models of LiBH₄ mechanically milled by graphite additive. Density-functional theory calculations have been performed to optimize the crystal structures of LiBH₄ inserted by different graphite fragments. It is found that the unsaturated sites introduced by graphite fragments are occupied by BH₃ complexes and H atoms. The dehydrogenation energies are calculated to investigate the dehydrogenation ability of LiBH₄ with graphite fragments. The results show that BH₃ complexes bonded with graphite fragments have lower dehydrogenation energy than pure LiBH₄, which is an important factor of the improvement of thermodynamic property of LiBH₄ system. The hydrogen diffusion behaviors of graphite fragments doped LiBH₄ are investigated by the nudged elastic band method. It is found that the hydrogen diffusion barriers of ¦Â-H (the H atoms of BH₃ complexes bonding with C atoms) diffusing to other sites are small in the LiBH₄/graphite fragment systems. The results show that the existence of ¦Â-H type significantly enhances the hydrogen diffusion kinetics of the graphite fragments doped LiBH₄.