Hydrogen storage covalent hydride

The highest gravimetric capacity element is LiH (12.7 wt%) shown in Fig. 12.3. Many of these hydrides are not practical as their thermodynamic properties are out of range as discussed earlier the only metal hydride that has practical volumetric hydrogen storage capacity is VH2 (at 2.8 atm.) which can be hydrided at room temperature. A covalent compound hydride... 

Hydrogen Storage Materials (Solid) for Fuel Cell Vehicles, Fig. 5 Table of the binary hydrides and the AUred-Rochow electronegativity [10]. Most elements react with hydrogen to form ionic, covalent, or metallic binary hydrides... 

Although the above hydrogen storage alloys can absorb and desorb hydrogen reversibly under a lower hydrogen pressure at lower temperature than those of stable ionic and covalent hydrides, the gravimetric density of hydrogen is small because the alloys are composed of heavy elements. 

HYDROGEN reacts with most of the metals to form chemical compounds— metal hydrides. Their properties, crystal structures and chemical bonding cover a wide range, including features of typical ionic, covalent, metallic and complex compounds. Metal hydrides are particularly useful for reversible storage of hydrogen in applications as an energy carrier. 

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