Improvement of hydrogen-storage properties of MgH2 by addition of Li3N, LiBH4, Fe and/or Ti

In order to increase hydrogen storage capacity of MgH2-based materials, Li3N, LiBH4, Fe, and/or Ti were added. Mixtures with compositions of 50MgH2–50Li3N, 40Mg–10MgH2–50Li3N, 68MgH2–17LiBH4–15Fe, and 70MgH2–17LiBH4–13Ti were prepared by reactive mechanical grinding and their hydrogen-storage properties were examined. 40Mg–10MgH2–50Li3N after hydriding–dehydriding cycling contains Mg3N2, LiMgN, LiOH, and MgO, LiH, and NH3·2H2O, suggesting a reaction of 6Mg + 4MgH2 + 4Li3N + 23H2O → Mg3N2 + LiMgN + 11LiOH + 3NH3·2H2O + 6MgO + 7H2. 70MgH2–17LiBH4–13Ti after hydriding–dehydriding cycling contained MgH2, TiH1.924, Mg, and MgO. Among the samples studied, 70MgH2–17LiBH4–13Ti had the highest hydriding rate in the beginning. The as-milled 70MgH2–17LiBH4–13Ti sample absorbed 3.33 wt% H for 5 min, 3.83 wt% H for 10 min, and 3.94 wt% H for 60 min at 573 K under 12 bar H2.

Absorbed hydrogen quantity Ha vs. time t curves at 573 K under 12 bar H2 for the as-milled 50MgH2–50Li3N, 40Mg–10MgH2–50Li3N, 68MgH2–17LiBH4–15Fe, and 70MgH2–17LiBH4–13Ti samples.Figure optionsDownload as PowerPoint slideHighlights
► Hydrogen-storage properties of MgH2 by addition of Li3N, LiBH4, Fe, and/or Ti.
► MgO or LiOH are formed by the reaction of MgH2 or Li3N with water vapor.
► 40Mg–10MgH2–50Li3N after cycling contained Mg3N2, LiMgN, LiOH, LiH, etc.
► 70MgH2–17LiBH4–13Ti absorbed 3.94 wt% H for 60 min at 573 K under 12 bar H2.