Hydrogen desorption/absorption properties of Li-Ca-N-H system

Tokoyoda Kazuhiko

Hino Satoshi

Ichikawa Takayuki

Okamoto Keisuke

Fujii Hironobu

Journal of Alloys and Compounds

Hydrogen storage properties of two ball-milled composites of Ca(NH2)2+2LiH and CaH2+2LiNH2 were investigated as a series of searching studies of high performance hydrogen storage materials. About 4.5 mass% hydrogen is desorbed from about 100 °C and the thermal desorption profiles show a peak around 200 and 220 °C for the composites of CaH2+2LiNH2 and Ca(NH2)2+2LiH, respectively, under a helium flow at 5 °C/min heating rate without any NH3 emission within our experimental accuracy. The powder X-ray diffraction and infrared absorption spectroscopy indicated that the dehydrogenated states of both composites form "an unknown imide phase" after heating up to 400 °C, while the dehydrogenated states after heating up to 200 °C in vacuum are the mixed phases of Li2NH and CaNH. The rehydrogenated state for the ball-milled composite of CaH2+2LiNH2 is transformed into the composite of Ca(NH2)2 and 2LiH by repeating the dehydrogenation and rehydrogenation cycles at 180~200 °C.

Hydrogen storage materials

Gas-solid reactions

ball-milling

calcium amide

Physics [ 420 ]

eng

Elsevier B.V.

Copyright (c) 2007 Elsevier B.V.

[ISSN] 0925-8388

[DOI] 10.1016/j.jallcom.2006.08.234

[NCID] AA10817249

[DOI] http://dx.doi.org/10.1016/j.jallcom.2006.08.234