Li2(NH2BH3)(BH4)/LiNH2BH3: The first metal amidoborane borohydride complex with inseparable amidoborane precursor for hydrogen storage

A novel lithium amidoborane borohydride complex, Li-2(NH2BH3)(BH4), was synthesized using mechanochemical method and its crystal structure was successfully determined by a combination of X-ray diffraction (XRD) analysis and first-principles calculations. Interestingly, this compound does not exist as a pure phase, but requires almost equivalent amount of amorphous LiAB as a stabilizing agent. In this paper, we report a careful study of the structure, property, and dehydrogenation mechanism of the 1:1 Li-2(NH2BH3)(BH4)/LiAB composite. This composite can release similar to 8 wt% H-2 at 100 degrees C via a two-step dehydrogenation process, with dehydrogenation ldnetics better than the parenting phases. The composite and its dehydrogenation products were characterized by the combined XRD, Fourier transformation infrared (FTIR) spectroscopy, and solid-state B-11 MAS NMR techniques. Selective deuterium labeling was performed to elucidate a reaction sequence for the hydrogen release by analyzing the released gases. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.