Effect of Hydrogen Back Pressure on Dehydrogenation Behavior of LiBH₄-Based Reactive Hydride Composites

Abstract

Hydrogen back pressure remarkably promotes the formation of metal boride during the dehydrogenation of 4LiBH4 + YH3, 6LiBH4 + CeH2 and 6LiBH4 + CaH2 composites, which seems to be a general phenomenon in LiBH4-based reactive hydride composites that enables mutual destabilization between LiBH4 and metal hydride. The formation of metal boride plays a crucial role in the reversible hydrogen storage properties of these composites. The dependence of the dehydrogenation behavior on hydrogen back pressure might be associated with the microstructural evolution of the dehydrogenation products formed by a solid−liquid reaction.

Hydrogen storage properties of rare earth (RE) borohydrides (RE = La, Er) in composite mixtures with LiBH4 and LiH

“…A similar destabilization effect has also been observed in other composites containing LiBH 4 and metal hydrides, e.g. 6LiBH 4 -CaH 2 [27,28] , 6LiBH 4 -CeH 2 [24,27,28] and 4LiBH 4 -YH 3 [27]. Gennari et al [13] recently investigated the thermal behavior and reversibility of 6LiBH 4 -RECl 3 composites (RE=Ce, Gd) with and without addition of LiH.…”

Hydrogen Sorption in Erbium Borohydride Composite Mixtures with LiBH4 and/or LiH

“…The cycling experiments were conducted using a heating/cooling rate of 5 • C·min −1 with a typical H 2 pressure of~100 bar for absorption and~3 bar for desorption. Hydrogen pressure was employed for all volumetric and in situ SR-PXD experiments, as similar conditions were reported to increase gas desorption compared to desorption under vacuum [17,27,45]. Data were collected using a Pilatus 2 M detector (DECTRIS Ltd., Baden-Daettwil, Switzerland) and a sample-to-detector distance of 146 mm at wavelengths of 0.77787 Å. Wavelength and sample-to-detector distance were calibrated from an NIST LaB 6 standard.…”

Direct Rehydrogenation of LiBH4 from H-Deficient Li2B12H12−x

“…Owing to the high thermal stability and low chemical reactivity, Li 2 B 12 H 12 is generally considered as a boron sink in the hydrogen sorption process of LiBH 4 -based compounds hindering the efficient rehydrogenation reaction. Many efforts have been taken to circumvent the formation of Li 2 B 12 H 12 in dehydrogenation process of LiBH 4 and to improve the reversibility [18][19][20][21][22][23][24][25][26][27][28][29]. However, much less work has been done on the hydrogenation properties of Li 2 B 12 H 12 itself, especially of the H-deficient Li 2 B 12 H 12−x formed from the decomposition of LiBH 4 , which is of great importance for improving the hydrogen storage function of LiBH 4 .…”