Other Metal-N-H Systems

After the discovery of the Li-Mg-N-Fl systems, many combinations of metal hydride (MFlx) and metal amide (M(NH2)x) were investigated to obtain suitable hydrogen storage properties. 

The mixture of MgFl2 and Mg(NFl2)2, the so-called the Mg-N-H system, was studied by Nakamori et al. [30], Leng et al. [31], Flu et al. [32] and Xie et al. [33], who showed a quite low starting temperature of hydrogen desorption compared with the Li-N-Fl system. The corresponding reaction can be written as (7.3 mass%)  

Recently, Wu [37] reported the crystal structure of the ternary imide Li2Ca(NH)2 which was determined using neutron powder diffraction data on a deuterated sample. In his paper, the reaction, Li2Ca(NH)2 + H2 LiNH2 + LiH + CaNH, was indicated. However, with respect to the reaction mechanism of the Li-Mg-N-H system [38], the reaction process in this report was thought to be stopped halfway. 

The Na-Li-N-H [14], Mg-Na-N-H [39], Ca-Na-N-H [40], Mg-Ca-N-H [41, 42] and Mg-Ca-Li-N-H [43] systems have also been investigated, where the metal elements used in these works were mainly limited to the alkali and alkaline earth 

Janot ef al. [48] prepared lithium aluminum amide (LiAl(NH2)4) and used it instead of LiNH2 in the Li-N-H system. The mixture of LiAl(NH2)4 and 4LiH released more than 5 mass % hydrogen at 130 °G. Ho vever, the experimental result of the hydrogenation indicated that this combination vould have a poor reversibility because of the existence of AlN after the dehydrogenation. 

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