Hydrogen Storage Properties of Lithium Aluminohydride Modified by Dopants and Mechanochemistry

摘要

Alkali metal aluminohydrides have high potential as solid hydrogen storage materials. They have been known for their irreversible dehydrogenation process below 100 atm until Bogdanovic et al (1, 2) succeeded in the re-hydrogenation of NaAlH4 below 70 atm. They achieved 4 wt.% H2 reversible capacity by doping NaAlH4 with Ti and/or Fe organo-metalic compounds as catalysts. This suggests that other alkali and, possibly alkaline earth metal aluminohydrides can be used for reversible hydrogen storage when modified by proper dopants. In this research, Zr27Ti9Ni38V5Mn16Cr5, LaNi4.85Sn0.15, Al3Ti, and PdCl2 were combined with LiAlH4 by ball-milling to study whether or not LiAlH4 is capable to both absorb and desorb hydrogen near ambient conditions. X-ray powder diffraction, differential thermal analysis, and scanning electron microscopy were employed for sample characterizations. All four compounds worked as catalysts in the dehydrogenation reactions of both LiAlH4 and Li3AlH6 by inducing the decomposition at lower temperature. However, none of them was applicable as catalyst in the reverse hydrogenation reaction at low to moderate hydrogen pressure.