Patent ID: 8163267

Claim:
A method of synthesizing magnesium-cobalt pentahydride, comprising: melting a magnesium (Mg) metal and a cobalt (Co) metal at a first temperature, wherein the content of the cobalt metal is substantially 30 atom percent (at %), and the first temperature is between the melting point of the magnesium metal and the melting point of the cobalt metal, thereby forming a molten metal; cooling the molten metal to a second temperature and then isothermally heating the molten metal for forming a MgCo 2 alloy, and removing unreacted pure magnesium, wherein the second temperature is between the first temperature and the melting point of the magnesium metal; cooling down the MgCo 2 alloy; performing a ball-milling step onto the MgCo 2 alloy and another magnesium metal to form metal mixture powder, wherein the mole ratio of the MgCo 2 alloy to the another magnesium metal is substantially 1:3; performing a hydrogenation step onto the metal mixture powder for up to 15 hours at a temperature of substantially 100° C. to 600° C. under a hydrogen pressure of substantially 6 atm (atmosphere) to 120 atm so as to form magnesium-cobalt pentahydride (Mg 2 CoH 5 ) without leaving residual pure cobalt, wherein the hydrogen absorption amount of the Mg 2 CoH 5 is substantially 2.5 mass percent (mass %) at 350° C., and the hydrogen desorption amount of the Mg 2 CoH 5 is substantially 2.0 mass % at 350° C.