Improvement of hydrogen-storage properties of MgH2 by Ni, LiBH4, and Ti addition

• DOI: 10.1016/j.ijhydene.2012.11.074
• Publication Date: 2012-12-21T16:47:41Z
• Authors: Myoung Youp Song; Young Jun Kwak; Hyung-Shik Shin; Seong Ho Lee; Byoung-Goan Kim
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract In this work, differently from our previous work, MgH 2 instead of Mg was used as a starting material. Ni, Ti, and LiBH 4 with a high hydrogen-storage capacity of 18.4 wt% were added. A sample with a composition of MgH 2 –10Ni–2LiBH 4 –2Ti was prepared by reactive mechanical grinding. MgH 2 –10Ni–2LiBH 4 –2Ti after reactive mechanical grinding contained MgH 2 , Mg, Ni, TiH 1.924 , and MgO phases. The activation of MgH 2 –10Ni–2LiBH 4 –2Ti for hydriding and dehydriding reactions was not required. At the number of cycles, n = 2, MgH 2 –10Ni–2LiBH 4 –2Ti absorbed 4.09 wt% H for 5 min, 4.25 wt% H for 10 min, and 4.44 wt% H for 60 min at 573 K under 12 bar H 2 . At n = 1, MgH 2 –10Ni–2LiBH 4 –2Ti desorbed 0.13 wt% H for 10 min, 0.54 wt% H for 20 min, 1.07 wt% H for 30 min, and 1.97 wt% H for 60 min at 573 K under 1.0 bar H 2 . The PCT (Pressure–Composition–Temperature) curve at 593 K for MgH 2 –10Ni–2LiBH 4 –2Ti showed that its hydrogen-storage capacity was 5.10 wt%. The inverse dependence of the hydriding rate on temperature is partly due to a decrease in the pressure differential between the applied hydrogen pressure and the equilibrium plateau pressure with the increase in temperature. The rate-controlling step for the dehydriding reaction of the MgH 2 –10Ni–2LiBH 4 –2Ti at n = 1 was analyzed.