Yoonyoung Kim

Microstructural Analysis of Dehydrogenation Products of the Ca(BH 4 ) 2 –MgH 2 Composite

The microstructural analysis of the dehydrogenation products of the Ca(BH₄)₂-MgH₂ composite was performed using transmission electron microscopy. It was found that nanocrystalline CaB₆ crystallites formed as a dehydrogenation product throughout the areas where the signals of Ca and Mg were simultaneously detected, in addition to relatively coarse Mg crystallites. The uniform distribution of the nanocrystalline CaB₆ crystallites appears to play a key role in the rehydrogenation of the dehydrogenation products, which implies that microstructure is a crucial factor determining the reversibility of reactive hydride composites.

Thermodynamics and sorption reaction of some light metal borohydrides for reversible hydrogen storage

There are several options to reduce the dehydrogenation temperature of light metal borohydrides and they include: i) alloying including cation or anion exchange, ii) size reduction, and iii) mutual destabilization reaction. Each of them has its own merits and demerits, but practical solutions would be emerged by proper combination of these options. Here, both thermodynamic properties and kinetic factors which have strong influence on dehydrogenation and hydrogenation reactions of some metal borohydride systems will be briefly reviewed.