In situ synchrotron diffraction studies of phase transitions and thermal decomposition of Mg(BH4)2 and Ca(BH4)2

Riktor, M.D.; Sørby, Magnus H.; Chłopek, Krzysztof; Fichtner, Maximilian; Buchter, F.; Züttel, Andreas; Hauback, Bjørn C.

doi:10.1039/b712750b

Cited by 140 publications

(174 citation statements)

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“…In the case of x ) 0.6, -Ca(BH 4 ) 2 transforms to δ-Ca(BH 4 ) 2 almost simultaneously with the eutectic melting, and the temperature marked in Figure 6 corresponds to the temperature at which δ-Ca(BH 4 ) 2 disappears. Here δ-Ca(BH 4 ) 2 appears at temperatures at more than 100°C lower than the case of pure Ca(BH 4 ) 2 , 32,38 which again hints at a rapid phase transformation in this composite system. In the case of x ) 0.8, δ-Ca(BH 4 ) 2 was not observed probably because Ca(BH 4 ) 2 melts completely before the -to δ-Ca(BH 4 ) 2 transition starts.…”

Section: Eutectic Meltingmentioning

confidence: 80%

“…Majzoub et al 27 predicted that γ-Ca(BH 4 ) 2 is metastable, but this point has not been proven experimentally. Another polymorph δ-Ca(BH 4 ) 2 reported by Riktor et al 32,38 appears at higher temperatures than -Ca(BH 4 ) 2 . No structural information has yet been given for δ-Ca(BH 4 ) 2 .…”

Section: Introductionmentioning

confidence: 85%

“…-, and γ-Ca(BH 4 ) 2 are usually found and the proportion of each phase is very sensitive to the preparation condition. 26,[32][33][34][35][36] Several in situ XRD experiments have shown that R-and γ-Ca(BH 4 ) 2 transform to -Ca(BH 4 ) 2 upon increasing temperature. Theoretical work based on density functional theory 26,27,37 supports this experimental observation that R-Ca(BH 4 ) 2 is stable at low temperatures and -Ca(BH 4 ) 2 at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite

et al. 2009

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LiBH 4 is one of the promising candidates for hydrogen storage materials because of its high gravimetric and volumetric hydrogen capacity. However, its high dehydrogenation temperature and limited reversibility has been a hurdle for its use in real applications. In an effort to overcome this barrier and to adjust the thermal stability, we make a composite system LiBH 4 -Ca(BH 4 ) 2 . In order to fully characterize this composite system we study xLiBH 4 + (1 -x)Ca(BH 4 ) 2 for several x values between 0 and 1, using differential scanning calorimetry, in situ synchrotron X-ray diffraction, thermogravimetric analysis, and mass spectrometry. Interestingly, this composite undergoes a eutectic melting at ca. 200°C in a wide composition range, and the eutectic composition lies between x ) 0.6 and 0.8. The decomposition characteristics and the hydrogen capacity of this composite vary with x, and the decomposition temperature is lower than both the pure LiBH 4 and Ca(BH 4 ) 2 at intermediate compositions, for example, for x ≈ 0.4, decomposition is finished below 400°C releasing about 10 wt % of hydrogen. Partial reversibility of this system was also confirmed for the first time for the case of a mixed borohydride composite.

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Section: Eutectic Meltingmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite

et al. 2009

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“…Mg(BH 4 ) 2 releases approximately 14.9 mass% of hydrogen when heated up to 870 K [56][57][58][59][60][61][62][63][64][65][66]. The dehydrogenation process is found to also proceed through multiple steps together with the formation of intermediate compounds [62,63,65], as summarized in Figure 2.…”

Section: Fundamentals Of Hydrogen Storage Propertiesmentioning

confidence: 94%

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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“…Mg(BH4)2 is considered as another promising hydrogen storage materials and it releases approximately 14.9 wt% of hydrogen when heated up to 870K [22,23,[85][86][87][88][89][90][91][92][93]. As discussed in Introduction, the dehydrogen process is found to go through multiple steps with formation of some stable intermediates such as MgB12H12 and MgH2 [21].…”

Section: Figure 3 Snapshots From Ab Initio Molecular Dynamics Trajecmentioning

confidence: 99%

Improvement on Hydrogen Storage Properties of Complex Metal Hydride

Li¹,

Zhang²

2012

Hydrogen Storage

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In situ synchrotron diffraction studies of phase transitions and thermal decomposition of Mg(BH4)2 and Ca(BH4)2

Cited by 140 publications

References 11 publications

Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite

Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite

Recent Progress in Metal Borohydrides for Hydrogen Storage

Improvement on Hydrogen Storage Properties of Complex Metal Hydride

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In situ synchrotron diffraction studies of phase transitions and thermal decomposition of Mg(BH4)2 and Ca(BH4)2

Cited by 140 publications

References 11 publications

Decomposition Reactions and Reversibility of the LiBH4−Ca(BH4)2 Composite

Decomposition Reactions and Reversibility of the LiBH4−Ca(BH4)2 Composite

Recent Progress in Metal Borohydrides for Hydrogen Storage

Improvement on Hydrogen Storage Properties of Complex Metal Hydride

Contact Info

Product

Resources

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Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite

Decomposition Reactions and Reversibility of the LiBH₄−Ca(BH₄)₂ Composite