Synthetic approaches to inorganic borohydrides

Hagemann, Hans‐Rudolf; Černý, Radovan

doi:10.1039/b927002g

Cited by 84 publications

(80 citation statements)

References 68 publications

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“…In this review, we focus on the recent progress in the dehydrogenation and rehydrogenation reactions of M(BH 4 ) n at controlled temperature and hydrogen pressure. Some several excellent reviews on M(BH 4 ) n are also available [2,[12][13][14][15][16][17][18].…”

Section: Open Accessmentioning

confidence: 99%

Recent Progress in Metal Borohydrides for Hydrogen Storage

et al. 2011

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Abstract:The prerequisite for widespread use of hydrogen as an energy carrier is the development of new materials that can safely store it at high gravimetric and volumetric densities. Metal borohydrides M(BH 4 ) n (n is the valence of metal M), in particular, have high hydrogen density, and are therefore regarded as one such potential hydrogen storage material. For fuel cell vehicles, the goal for on-board storage systems is to achieve reversible store at high density but moderate temperature and hydrogen pressure. To this end, a large amount of effort has been devoted to improvements in their thermodynamic and kinetic aspects. This review provides an overview of recent research activity on various M(BH 4 ) n , with a focus on the fundamental dehydrogenation and rehydrogenation properties and on providing guidance for material design in terms of tailoring thermodynamics and promoting kinetics for hydrogen storage.

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Section: Open Accessmentioning

confidence: 99%

Recent Progress in Metal Borohydrides for Hydrogen Storage

et al. 2011

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“…13−16 Because of the widely used mechanochemical synthesis of novel borohydrides starting from metal borohydrides and halides, most bimetallic systems contain metal halides as secondary phases as well as halide substitution on the borohydride sites. 17,18 Besides stabilizing new phases that may not exist in Cl-free systems, 19 this considerably decreases gravimetric capacities of the novel hydrides. From this point of view, it is important to carry out synthesis of new borohydrides by addition with other complex forming borohydrides, like Al(BH 4 ) 3 .…”

Section: ■ Introductionmentioning

confidence: 99%

The First Halide-Free Bimetallic Aluminum Borohydride: Synthesis, Structure, Stability, and Decomposition Pathway

et al. 2013

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Interaction of solid KBH 4 with liquid Al(BH 4 ) 3 at room temperature yields a solid bimetallic borohydride KAl(BH 4 ) 4 . According to the synchrotron X-ray powder diffraction, its crystal structure (space group Fddd, a = 9.7405(3), b = 12.4500(4), and c = 14.6975(4) Å) contains a substantially distorted tetrahedral [Al(BH 4 ) 4 ]− anion, where the borohydride groups are coordinated to aluminum atoms via edges. The η -coordination of BH 4− is confirmed by the infrared and Raman spectroscopies. The title compound is the first aluminum-based borohydride complex not stabilized by halide anions or by bulky organic cations. It is not isostructural to bimetallic chlorides, where more regular tetrahedral AlCl 4 − anions are present. Instead, it is isomorphic to the LT phase of TbAsO 4 and can be also viewed as consisting of two interpenetrated dia-type nets where BH 4 ligand is bridging Al and K cations. Variable temperature X-ray powder diffraction, TGA, DSC, and TGA-MS data reveal a single step of decomposition at 160°C, with an evolution of hydrogen and some amount of diborane. Aluminum borohydride is not released in significant amounts; however, some crystalline KBH 4 forms upon decomposition. The higher decomposition temperature than in chloride-substituted Li−Al (70°C) and Na−Al (

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“…As an alternative method, the solvent-based synthesis of borohydrides has been used for over 50 years with the advantage of removing the alkali metal chloride (i.e., LiCl) [28], which is necessary to increase the hydrogen capacity. The halide-free synthesis in this paper is based on a mechanochemical synthesis [33] and wet-chemical extraction, as described by Hagemann et al [34,35].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Rare earth (RE) metal borohydrides have recently been receiving attention as possible hydrogen storage materials and solid-state Li-ion conductors. In this paper, the decomposition and reabsorption of Er(BH 4 ) 3 in composite mixtures with LiBH 4 and/or LiH were investigated. The composite of 3LiBH 4 + Er(BH 4 ) 3 + 3LiH has a theoretical hydrogen storage capacity of 9 wt %, nevertheless, only 6 wt % hydrogen are accessible due to the formation of thermally stable LiH. Hydrogen sorption measurements in a Sieverts-type apparatus revealed that during three desorption-absorption cycles of 3LiBH 4 + Er(BH 4 ) 3 + 3LiH, the composite desorbed 4.2, 3.7 and 3.5 wt % H for the first, second and third cycle, respectively, and thus showed good rehydrogenation behavior. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) after ball milling of Er(BH 4 ) 3 + 6LiH resulted in the formation of LiBH 4 , revealing that metathesis reactions occurred during milling in these systems. Impedance spectroscopy of absorbed Er(BH 4 ) 3 + 6LiH showed an exceptional high hysteresis of 40-60 K for the transition between the high and low temperature phases of LiBH 4 , indicating that the high temperature phase of LiBH 4 is stabilized in the composite.

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Synthetic approaches to inorganic borohydrides

Cited by 84 publications

References 68 publications

Recent Progress in Metal Borohydrides for Hydrogen Storage

Recent Progress in Metal Borohydrides for Hydrogen Storage

The First Halide-Free Bimetallic Aluminum Borohydride: Synthesis, Structure, Stability, and Decomposition Pathway

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

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