Destabilization of Li-based complex hydrides

Fundamental researches on complex hydrides are recently of great importance to develop practical hydrogen storage materials with higher gravimetric hydrogen densities than those of conventional materials. First, in this paper, we clarify the correlation between B-H atomistic vibrations in [BH4](-)-anion and melting temperatures of MBH4 (M = Li, Na, and K) as indexes of hydrogen desorption (decomposition) temperatures. This investigation implies that partial cation substitutions using smaller sized- and/or higher valenced-cations with higher electronegativities might provide higher energy modes of Raman spectra, and then, lower hydrogen desorption (decomposition) temperatures. Next, as an example, the hydrogen desorption properties of LiNH2 and its partial cation substitution are preliminary examined. The starting and ending temperatures for the hydrogen desoprtion reaction are actually lowered about 50 K by the partial cation substitution of Li by Mg. (C) 2003 Elsevier B.V. All rights reserved.