A Novel Li-Ca-B-H Complex Borohydride: Its Synthesis and Hydrogen Storage Properties

作者：Jiang, Kun; Xiao, Xuezhang^*; Deng, Shuaishuai; Zhang, Miao; Li, Shouquan; Ge, Hongwei; Chen, Lixin

来源：Journal of Physical Chemistry C, 2011, 115(40): 19986-19993.

DOI：10.1021/jp203896w

• METAL
• LISC(BH4)(4)
• DESORPTION
• DENSITY
• NMR

The synthesis and hydrogen-storage properties of the mixed alkali metal and alkaline-earth metal borohydride are systematically investigated. It is found that mechanical milling a mixture of LiBH4 and CaCl2 with molar ratio of 3:1 in tetrahydrofuran (THF) forms a new LiBH4 center dot Ca(BH4)(2)center dot 2THF compound. Thermal analysis indicates that the decomposition process of the new compound involves four steps: (1) LiBH4 center dot Ca(BH4)(2)center dot 2THF decomposes first into high temperature phase of LiBH4, CaB6, and an intermediate phase Ca-B-H-Cl hydride and synchronously releases a large number of H-2 and THF gas together with less B2H6; (2) the eutectic melting of LiBH4 and Ca-B-H-Cl hydride; (3) Ca-B-H-Cl hydride decomposes into CaHCl, CaB6, and a little H-2; (4) LiBH4 reacts with CaHCl, generating H-2, CaH2, CaB6, LiH, and LiCl. The first dehydrogenation step starts at ca. 70 degrees C, which is much lower than that of the pristine LiBH4 and Ca(BH4)(2). According to Kissenger's equation, the activation energies of the different dehydrogenation steps are respectively 291.95, 132.06, and 117.13 kJ/mol, except the second decomposition step. Moreover, this new compound LiBH4 center dot Ca(BH4)(2)center dot 2THF is proved to be partially reversible, which can release 5.63 wt % hydrogen in the second rehydrogenation/dehydrogenation cycle.

• 出版日期2011-10-13
• 单位浙江大学