Potential and Reaction Mechanism of Li−Mg−Al−N−H System for Reversible Hydrogen Storage

Abstract

Complex metal hydrides are attracting much attention as a class of candidate materials for hydrogen storage. Lithium-based complex hydrides, including lithium aluminum hydrides (LiAlH4 and Li3AlH6), are among the most promising materials, owing to their high hydrogen contents. In the present work, we investigated the dehydrogenation/rehydrogenation reactions of a combined system of Li3AlH6 and Mg(NH2)2, which has a theoretical hydrogen capacity of 6.5 wt %. Thermogravimetric analysis of hydrogenated 2/3Al−Li2Mg(NH)2 (doped with 4 wt % TiCl3) indicated that a large amount of hydrogen (∼6.2 wt %) can be stored under 300 °C and 172 bar of hydrogen pressure. The FT-IR and NMR results showed that the reaction between Li3AlH6 and Mg(NH2)2 is reversible. Further, a short-cycle experiment has demonstrated that the new combined material system of alanates and amides can maintain its hydrogen storage capacity upon cycling of the dehydrogenation/rehydrogenation reactions.

Synthesis and crystal structure of a novel nitride hydride Sr2LiNH2

“…In order to improve the thermodynamic properties of binary Li-N-H system, Li was compositionally substituted by other elements, and several types of ternary or multinary metal-N-H systems (e.g. Li-Mg-N-H [5][6][7][8][9], Li-Ca-N-H [10,11], Li-Al-N-H [12][13][14], Li-B-N-H [12,15], Li-Co-N-H [16] and Li-Mg-Al-N-H [17,18]) were developed.…”

“…One is investigating the hydrogen absorption/desorption property [1][2][3][4][5][8][9][10][11][12][13][14][15][16][17][18]; the other is revealing the reaction mechanism involved in the hydrogen absorption/desorption processes [1,6,7,[14][15][16]21]. It was reported that the new ternary imides with mixed alkali and alkaline earth cations, Li 2 Mg(NH) 2 and Li 2 Ca(NH) 2 , were formed along with the dehydrogenation reaction in the Li-Mg-N-H and Li-Ca-N-H systems, respectively [5,8,11,[19][20][21].…”

Hydrogen storage properties of the Mg–Ti–H system prepared by high-energy–high-pressure reactive milling

“…Compared to the physical approaches such as liquefaction and compression, hydrogen storage in the solid state has merits in terms of high volumetric and gravimetric hydrogen contents and, most importantly, safety [1]. Research in many laboratories around the world has focused on the solid-state hydrogen storage materials that are based on three primary approaches: (1) using inorganic solid hydride materials that have reversible dehydrogenation and rehydrogenation characteristics [2][3][4][5][6][7][8][9], (2) using the hydrolysis of alkali-and alkaline-earth metal hydrides and complex hydrides (such as MgH 2 , LiH, LiAlH 4 and LiBH 4 ) [10,11] and (3) using carbon or other adsorbent materials to store hydrogen based on surface adsorption and desorption [12][13][14]. The critical characteristic properties of a solid hydrogen storage material include storage capacity, dehydrogenation temperature, plateau pressure and the reversibility of dehydrogenation and rehydrogenation.…”

Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

“…Lithium aluminum hydride (LiAlH 4 ) has a high hydrogen storage capacity (10.5 wt % H 2 ) and an excellent performance of hydrogen desorption at low temperature; thus, it has received significant attention from researchers. LiAlH 4 decomposes through a two-step process into Al, LiH, and H 2 at T < 250 • C through the intermediate Li 3 AlH 6 , according to reaction scheme (3) [24][25][26][27][28][29].…”