Preparation of MgH2 composite with a composition of 40%MgH2 + 30%LiBH4 + 30%(2LiBH4 + MgF2)

A mixture of containing two chemical equivalents of lithium borohyride and one equivalent of magnesium fluoride is known to yield hydrogen in an amount of about 7.6 wt% of the mixture when heated to about 150 °C at atmospheric pressure by the following reaction; 2LiBH4 + MgF2 = 2LiF + MgB2 + 4H2. In order to increase hydrogen storage capacity of Mg-based materials, a mixture with a composition of 2LiBH4 + MgF2 and LiBH4with a higher hydrogen storage capacity of 18.4 wt% were added to MgH2. MgH2 composite with a composition of 40 wt%MgH2 + 30 wt%LiBH4 + 30 wt%(2LiBH4 + MgF2) was prepared by reactive mechanical grinding. The hydrogen storage properties of the sample were then examined. Hydrogen content vs. desorption time curves for consecutive 1st desorptions of 40 wt%MgH2 + 30 wt%LiBH4 + 30 wt%(2LiBH4 + MgF2) at 533–873 K showed that the total desorbed hydrogen quantity for consecutive 1st desorptions is 7.07 wt%.

Hydrogen content vs. desorption time curves for consecutive 1st desorptions of 40 wt%MgH2 + 30 wt%LiBH4 + 30 wt%(2LiBH4 + MgF2) at 533–873 K.Figure optionsDownload as PowerPoint slideHighlights
► Addition of MgF2 and LiBH4 with a higher hydrogen storage capacity to MgH2.
► Preparation of 40%MgH2 + 30%LiBH4 + 30% (2LiBH4 + MgF2) composite.
► Examination of desorption properties of the composite.
► Total desorbed hydrogen quantity for consecutive 1st desorptions of 7.07 wt%.
► Reactions of LiBH4 → LiH + B + (3/2)H2, and 2LiBH4 + MgF2 → 2LiF + MgB2 + 4H2.