Superior Hydrogen Exchange Effect in the MgH 2 −LiBH 4 System

The MgH 2 −LiBH 4 system is one of the promising hydrogen storage materials. In this system, it was found that there was a mutual interaction between the two hydrides, but its detailed mechanism has not been clarified yet. In this work, we found an “H-D” exchange between MgD 2 and LiBH 4 during heating. IR absorption spectroscopy revealed that the peak of “B-D” vibration appeared at 275 °C below the melting point, indicating that this exchange proceeded even in solid phases. The hydrogen desorption properties of the composite of catalyst-doped MgH 2 and LiBH 4 under inert gas were investigated by mass spectrometry. The results showed that the hydrogen desorption temperature of the first step was over 300 °C, in spite of catalyst-doped MgH 2 being able to release hydrogen at 200 °C. The above results suggest the hydrogen desorption from catalyst-doped MgH 2 is somehow suppressed by the hydrogen exchange effect between MgH 2 and LiBH 4 .