De-hydrogenation/Rehydrogenation Properties and Reaction Mechanism of AmZn(NH2)n-2nLiH Systems (A = Li, K, Na, and Rb)

With the aim to find suitable hydrogen storage materials for stationary and mobile applica-tions, multi-cation amide-based systems have attracted considerable attention, due to their unique hydrogenation kinetics. In this work, Am Zn(NH2)n (with A = Li, K, Na, and Rb) were synthesized via an ammonothermal method. The synthesized phases were mixed via ball milling with LiH to form the systems Am Zn(NH2)n-2nLiH (with m = 2, 4 and n = 4, 6), as well as Na2 Zn(NH2)4·0.5NH3-8LiH. The hydrogen storage properties of the obtained materials were investigated via a combination of calorimetric, spectroscopic, and diffraction methods. As a result of the performed analyses, Rb2 Zn(NH2)4-8LiH appears as the most appealing system. This composite, after de-hydrogenation, can be fully rehydrogenated within 30 s at a temperature between 190◦ C and 200◦ C under a pressure of 50 bar of hydrogen.