J. Phys. Chem. C 2007, 111, 12129-12134
12129
Potential of Binary Lithium Magnesium Nitride for Hydrogen Storage Applications Jun Lu, Zhigang Zak Fang,* Young Joon Choi, and Hong Yong Sohn Department of Metallurgical Engineering, UniVersity of Utah, 135 South 1460 East Room 412, Salt Lake City, Utah 84112 ReceiVed: May 2, 2007; In Final Form: June 16, 2007
Metal hydrides and amides are potential candidate materials for hydrogen storage. Lithium- and magnesiumbased material systems are among the most promising materials owing to their high hydrogen contents. In the present work, we investigated hydrogenation/dehydrogenation reactions of a binary nitride, LiMgN. LiMgN can be formed by a reaction of MgH2 with LiNH2 in 1:1 ratio. The reaction also releases approximately ∼8.1 wt % H2 (theoretical value is 8.2 wt %) between 160 and 220 °C. The reaction product LiMgN can be rehydrogenated by reacting with H2 under 2000 psi of hydrogen pressure and 160 °C with a small amount of TiCl3 doping. TGA results showed that about 8.0 wt % of hydrogen was stored in TiCl3-doped LiMgN during the hydrogenation process. The reversible hydrogenation and dehydrogenation mechanisms involving LiMgN and H2 are discussed.
1. Introduction In recent years, a great deal of research and development effort on solid hydrogen storage materials has been focused on inorganic solid metal hydrides. Typically, these materials are complex metal hydrides of light metals of three categories: alanates,1-10 borohydrides,11-14 and hydrides/amides15-25 such as sodium alanates (NaAlH4), lithium borohydride (LiBH4), and lithium hydride/lithium amide (LiH/LiNH2). The primary driving force behind the interest in these complex metal hydrides versus simple metal hydrides such as LiH and MgH2 is that the latter are too stable at low temperatures (
