Pressure-enhanced dehydrogenation reaction of the LiBH4–YH3 composite

Abstract

The increase in hydrogen back pressure unexpectedly enhances the overall dehydrogenation reaction rate of the 4LiBH(4) + YH(3) composite significantly. Also, argon back pressure has a similar influence on the composite. Gas back pressure seems to enhance the dehydrogenation reaction by kinetically suppressing the formation of the diborane by-product.

Pressure and temperature dependence of the decomposition pathway of LiBH4

“…Higher hydrogen pressures, which will slow the decomposition of LiBH 4 , are found to be more favourable for the formation of borides. 39,40 In the present work, we have demonstrated that the knowledge of the thermodynamic properties of the hydride and its possible decomposition products and intermediates allows flexibility in selection of the decomposition pathway by tuning the external parameters such as pressure and temperature. In this way, it is possible that, unwanted by-products or boron sinks that prevent reversibility can be circumvented.…”

Improved hydrogen storage reversibility of LiBH4 destabilized by Y(BH4)3 and YH3

“…The ball milling of LiBH 4 with a variety of hydrides including MgH 2 [6e9], CaH 2 [10,11], CeH 2 [10,12e14], YH 3 [12,15,16] and LaH 2 [17] is an effective approach to modify the thermodynamic stability of LiBH 4 . The addition of a hydride to LiBH 4 leads to the formation of more stable end products (metal boride), reducing the overall enthalpy change of the dehydrogenation reaction and thus the dehydrogenation temperature.…”

Complex and liquid hydrides for energy storage

“…These mostly amorphous higher borane byproducts are quite stable thermodynamically, and they seem to be more difficult to rehydrogenate than the competing metal borides. Another issue is the influence of the hydrogen back/partial pressure on the formation of the dodecaboranes instead of metal borides [231][232][233]. When the dehydrogenation reaction occurs below a critical hydrogen partial pressure at a given temperature, it tends to form dodecaborane, which seems not to readily react with the metal hydrides to form metal borides.…”