| Abstract
| - This paper deals with the possibility of using compounds in the Li−Al−N−H system as hydrogen storagematerials. First, the LiAl(NH2)4 phase is prepared from LiAlH4 reacting in liquid ammonia at room temperature.The thermal decomposition of LiAl(NH2)4 under primary vacuum leads to the release, at 138 °C, of twomoles of NH3 per formula unit and the formation of LiAl(NH)2. This study mainly concerns the trapping ofammonia by adding an adequate amount of LiH to LiAl(NH2)4 in order to desorb hydrogen at low temperature.Indeed, a 1:4 LiAl(NH2)4:LiH mixture prepared by ball-milling is able to desorb more than 5.0 wt % ofhydrogen at 130 °C. This is remarkable as the desorption occurs at a temperature about 60 °C lower than the1:2 Mg(NH2)2:LiH mixture reported in the literature. The first attempts of rehydrogenation at 130 °C are,however, disappointing, due to the low stability of LiAl(NH)2. This imide is rapidly decomposed into LiNH2and AlN, the latter being inert toward hydrogen at low temperature, which explains the lack of reversibilityof the hydrogen storage process in this Li−Al−N−H system.
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