Effects of Stoichiometry on the H2‐Storage Properties of Mg(NH2)2–LiH–LiBH4 Tri‐Component Systems

The hydrogen desorption pathways and storage properties of 2 Mg(NH₂)₂–3 LiH–x LiBH₄ samples (x =0, 1, 2, and 4) were investigated systematically by a combination of pressure composition isotherm (PCI), differential scanning calorimetric (DSC), and volumetric release methods. Experimental results showed that the desorption peak temperatures of 2 Mg(NH₂)₂–3 LiH–x LiBH₄ samples were approximately 10–15 °C lower than that of 2 Mg(NH₂)₂–3 LiH. The 2 Mg(NH₂)₂–3 LiH–4 LiBH₄ composite in particular began to release hydrogen at 90 °C, thereby exhibiting superior dehydrogenation performance. All of the LiBH₄‐doped samples could be fully dehydrogenated and re‐hydrogenated at a temperature of 143 °C. The high hydrogen pressure region (above 50 bar) of PCI curves for the LiBH₄‐doped samples rose as the amount of LiBH₄ increased. LiBH₄ changed the desorption pathway of the 2 Mg(NH₂)₂–3 LiH sample under a hydrogen pressure of 50 bar, thereby resulting in the formation of MgNH and molten LiNH₂–2 LiBH₄]. That is different from the dehydrogenation pathway of 2 Mg(NH₂)₂–3 LiH sample without LiBH₄, which formed Li₂Mg₂N₃H₃ and LiNH₂, as reported previously. In addition, the results of DSC analyses showed that the doped samples exhibited two independent endothermic events, which might be related to two different desorption pathways.