A process for synthesizing the Li-Mg-N-H hydrogen storage system from Mg and LiNH2

Okamoto Keisuke

Tokoyoda Kazuhiko

Ichikawa Takayuki

Fujii Hironobu

Journal of Alloys and Compounds

We successfully established a method to synthesize the Li-Mg-N-H hydrogen storage system composed of Mg(NH2)2 and LiH from Mg and LiNH2 as starting materials. First of all, Mg and Li2NH were homogeneously mixed by ball-milling for 2 h under 1 MPa argon atmosphere. After that, the mixture was heat-treated at 250 °C for 16 h under vacuum condition to be transformed into Mg3N2 and Li2NH. Target materials, Mg(NH2)2 and LiH, were synthesized by a further heat-treatment for Mg3N2 and Li2NH at 200 °C under 10 MPa hydrogen atmosphere for 12 h. The phases in the sample at each processing stage were examined by X-ray diffraction and Fourier transformation infra-red absorption measurements and confirmed to be the expected ones. From experimental results of a thermal desorption mass spectroscopy, the final hydrogenated sample indicated that ~7 mass% hydrogen was desorbed starting from about 150 °C and peaked around 230 °C under helium flow condition at 5 °C/min heating rate without ammonia emission in our experimental accuracy.

hydrogen storage materials

mechanochemical synthesis

X-ray diffraction

thermal analysis

Physics [ 420 ]

eng

Elsevier B.V.

Copyright (c) 2006 Elsevier B.V.

[ISSN] 0925-8388

[DOI] 10.1016/j.jallcom.2006.05.119

[NCID] AA10817249

[DOI] http://dx.doi.org/10.1016/j.jallcom.2006.05.119