Destabilization of LiBH4 by mixing with LiNH2

It was revealed that LiBH4 is destabilized by mixing with LiNH2 and the mixture desorbs a large amount of hydrogen. First-principles calculations predicted that the enthalpies of dehydrogenation for LiBH4 alone and the mixture of LiBH4 + 2 LiNH2 are 75 kJ/molH2 and 23 kJ/molH2, respectively. Motivated by this prediction, we experimentally examined the dehydrogenation properties for LiBH4 and the mixture under hydrogen pressure. The amounts of desorbed hydrogen from LiBH4 and the mixture at 703 K and 522 K were 10.6 mass % and 7.8 mass %, respectively. The dehydrogenation pressure of the mixture was much higher than that of LiBH4 alone, although the mixture was measured at approximately 180 K lower temperature. This result suggests that the mixture is much unstable as compared with LiBH4 alone.