Mechanism of novel reaction from LiNH2 and LiH to Li2NH and H2 as a promising hydrogen storage system

The mechanism of the hydrogen desorption (HD) reaction from the 1:1 mixture of lithium amide (LiNH2) and lithium hydride (LiH) to lithium imide (Li2NH) and hydrogen (H-2) has been proposed on the basis of our experimental results in this paper. The proposed model is constituted by 2 kinds of elementary reactions: the one is that 2LiNH(2) decomposes to Li2NH and ammonia (NH3) the other is that the emitted NH3 reacts with LiH and transforms into LiNH2 and H-2. Since the former and the latter reactions are, respectively, endothermic and exothermic, the HD reaction corresponding to the latter reaction occurs as soon as LiNH2 has decomposed into Li2NH and NH3. Therefore, the HD reaction can be understood by the following processes: at the first step, LiNH2 decomposes into Li2NH/(2) + NH3/2, and then the emitted NH3/2 quickly reacts with LiH/2, transforming into LiNH2/2 + H-2/2; at the second one, the produced LiNH2/2 decomposes to Li2NH/4 + NH3/4, and then NH3/4 + LiH/4 transform to LiNH2/4 + H-2/4, and such successive steps continue until LiNH2 and LiH completely transform into Li2NH and H-2, even at low temperatures, by the catalytic effect of TiCl3.(.)